rhg: add a config option to fall back immediately

This is useful for debugging the behavior of the "default" `hg` in tests
without having to manually substitute the fallback path.

mercurial/helptext/config.txt

@@ -1,3324 +1,3332 b''
 The Mercurial system uses a set of configuration files to control
 aspects of its behavior.
 
 Troubleshooting
 ===============
 
 If you're having problems with your configuration,
 :hg:`config --source` can help you understand what is introducing
 a setting into your environment.
 
 See :hg:`help config.syntax` and :hg:`help config.files`
 for information about how and where to override things.
 
 Structure
 =========
 
 The configuration files use a simple ini-file format. A configuration
 file consists of sections, led by a ``[section]`` header and followed
 by ``name = value`` entries::
 
   [ui]
   username = Firstname Lastname <[e-mail]>
   verbose = True
 
 The above entries will be referred to as ``ui.username`` and
 ``ui.verbose``, respectively. See :hg:`help config.syntax`.
 
 Files
 =====
 
 Mercurial reads configuration data from several files, if they exist.
 These files do not exist by default and you will have to create the
 appropriate configuration files yourself:
 
 Local configuration is put into the per-repository ``<repo>/.hg/hgrc`` file.
 
 Global configuration like the username setting is typically put into:
 
 .. container:: windows
 
   - ``%USERPROFILE%\mercurial.ini`` (on Windows)
 
 .. container:: unix.plan9
 
   - ``$HOME/.hgrc`` (on Unix, Plan9)
 
 The names of these files depend on the system on which Mercurial is
 installed. ``*.rc`` files from a single directory are read in
 alphabetical order, later ones overriding earlier ones. Where multiple
 paths are given below, settings from earlier paths override later
 ones.
 
 .. container:: verbose.unix
 
   On Unix, the following files are consulted:
 
   - ``<repo>/.hg/hgrc-not-shared`` (per-repository)
   - ``<repo>/.hg/hgrc`` (per-repository)
   - ``$HOME/.hgrc`` (per-user)
   - ``${XDG_CONFIG_HOME:-$HOME/.config}/hg/hgrc`` (per-user)
   - ``<install-root>/etc/mercurial/hgrc`` (per-installation)
   - ``<install-root>/etc/mercurial/hgrc.d/*.rc`` (per-installation)
   - ``/etc/mercurial/hgrc`` (per-system)
   - ``/etc/mercurial/hgrc.d/*.rc`` (per-system)
   - ``<internal>/*.rc`` (defaults)
 
 .. container:: verbose.windows
 
   On Windows, the following files are consulted:
 
   - ``<repo>/.hg/hgrc-not-shared`` (per-repository)
   - ``<repo>/.hg/hgrc`` (per-repository)
   - ``%USERPROFILE%\.hgrc`` (per-user)
   - ``%USERPROFILE%\Mercurial.ini`` (per-user)
   - ``%HOME%\.hgrc`` (per-user)
   - ``%HOME%\Mercurial.ini`` (per-user)
   - ``HKEY_LOCAL_MACHINE\SOFTWARE\Mercurial`` (per-system)
   - ``<install-dir>\hgrc.d\*.rc`` (per-installation)
   - ``<install-dir>\Mercurial.ini`` (per-installation)
   - ``%PROGRAMDATA%\Mercurial\hgrc`` (per-system)
   - ``%PROGRAMDATA%\Mercurial\Mercurial.ini`` (per-system)
   - ``%PROGRAMDATA%\Mercurial\hgrc.d\*.rc`` (per-system)
   - ``<internal>/*.rc`` (defaults)
 
   .. note::
 
    The registry key ``HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Mercurial``
    is used when running 32-bit Python on 64-bit Windows.
 
 .. container:: verbose.plan9
 
   On Plan9, the following files are consulted:
 
   - ``<repo>/.hg/hgrc-not-shared`` (per-repository)
   - ``<repo>/.hg/hgrc`` (per-repository)
   - ``$home/lib/hgrc`` (per-user)
   - ``<install-root>/lib/mercurial/hgrc`` (per-installation)
   - ``<install-root>/lib/mercurial/hgrc.d/*.rc`` (per-installation)
   - ``/lib/mercurial/hgrc`` (per-system)
   - ``/lib/mercurial/hgrc.d/*.rc`` (per-system)
   - ``<internal>/*.rc`` (defaults)
 
 Per-repository configuration options only apply in a
 particular repository. This file is not version-controlled, and
 will not get transferred during a "clone" operation. Options in
 this file override options in all other configuration files.
 
 .. container:: unix.plan9
 
   On Plan 9 and Unix, most of this file will be ignored if it doesn't
   belong to a trusted user or to a trusted group. See
   :hg:`help config.trusted` for more details.
 
 Per-user configuration file(s) are for the user running Mercurial.  Options
 in these files apply to all Mercurial commands executed by this user in any
 directory. Options in these files override per-system and per-installation
 options.
 
 Per-installation configuration files are searched for in the
 directory where Mercurial is installed. ``<install-root>`` is the
 parent directory of the **hg** executable (or symlink) being run.
 
 .. container:: unix.plan9
 
   For example, if installed in ``/shared/tools/bin/hg``, Mercurial
   will look in ``/shared/tools/etc/mercurial/hgrc``. Options in these
   files apply to all Mercurial commands executed by any user in any
   directory.
 
 Per-installation configuration files are for the system on
 which Mercurial is running. Options in these files apply to all
 Mercurial commands executed by any user in any directory. Registry
 keys contain PATH-like strings, every part of which must reference
 a ``Mercurial.ini`` file or be a directory where ``*.rc`` files will
 be read.  Mercurial checks each of these locations in the specified
 order until one or more configuration files are detected.
 
 Per-system configuration files are for the system on which Mercurial
 is running. Options in these files apply to all Mercurial commands
 executed by any user in any directory. Options in these files
 override per-installation options.
 
 Mercurial comes with some default configuration. The default configuration
 files are installed with Mercurial and will be overwritten on upgrades. Default
 configuration files should never be edited by users or administrators but can
 be overridden in other configuration files. So far the directory only contains
 merge tool configuration but packagers can also put other default configuration
 there.
 
 On versions 5.7 and later, if share-safe functionality is enabled,
 shares will read config file of share source too.
 `<share-source/.hg/hgrc>` is read before reading `<repo/.hg/hgrc>`.
 
 For configs which should not be shared, `<repo/.hg/hgrc-not-shared>`
 should be used.
 
 Syntax
 ======
 
 A configuration file consists of sections, led by a ``[section]`` header
 and followed by ``name = value`` entries (sometimes called
 ``configuration keys``)::
 
     [spam]
     eggs=ham
     green=
        eggs
 
 Each line contains one entry. If the lines that follow are indented,
 they are treated as continuations of that entry. Leading whitespace is
 removed from values. Empty lines are skipped. Lines beginning with
 ``#`` or ``;`` are ignored and may be used to provide comments.
 
 Configuration keys can be set multiple times, in which case Mercurial
 will use the value that was configured last. As an example::
 
     [spam]
     eggs=large
     ham=serrano
     eggs=small
 
 This would set the configuration key named ``eggs`` to ``small``.
 
 It is also possible to define a section multiple times. A section can
 be redefined on the same and/or on different configuration files. For
 example::
 
     [foo]
     eggs=large
     ham=serrano
     eggs=small
 
     [bar]
     eggs=ham
     green=
        eggs
 
     [foo]
     ham=prosciutto
     eggs=medium
     bread=toasted
 
 This would set the ``eggs``, ``ham``, and ``bread`` configuration keys
 of the ``foo`` section to ``medium``, ``prosciutto``, and ``toasted``,
 respectively. As you can see there only thing that matters is the last
 value that was set for each of the configuration keys.
 
 If a configuration key is set multiple times in different
 configuration files the final value will depend on the order in which
 the different configuration files are read, with settings from earlier
 paths overriding later ones as described on the ``Files`` section
 above.
 
 A line of the form ``%include file`` will include ``file`` into the
 current configuration file. The inclusion is recursive, which means
 that included files can include other files. Filenames are relative to
 the configuration file in which the ``%include`` directive is found.
 Environment variables and ``~user`` constructs are expanded in
 ``file``. This lets you do something like::
 
   %include ~/.hgrc.d/$HOST.rc
 
 to include a different configuration file on each computer you use.
 
 A line with ``%unset name`` will remove ``name`` from the current
 section, if it has been set previously.
 
 The values are either free-form text strings, lists of text strings,
 or Boolean values. Boolean values can be set to true using any of "1",
 "yes", "true", or "on" and to false using "0", "no", "false", or "off"
 (all case insensitive).
 
 List values are separated by whitespace or comma, except when values are
 placed in double quotation marks::
 
   allow_read = "John Doe, PhD", brian, betty
 
 Quotation marks can be escaped by prefixing them with a backslash. Only
 quotation marks at the beginning of a word is counted as a quotation
 (e.g., ``foo"bar baz`` is the list of ``foo"bar`` and ``baz``).
 
 Sections
 ========
 
 This section describes the different sections that may appear in a
 Mercurial configuration file, the purpose of each section, its possible
 keys, and their possible values.
 
 ``alias``
 ---------
 
 Defines command aliases.
 
 Aliases allow you to define your own commands in terms of other
 commands (or aliases), optionally including arguments. Positional
 arguments in the form of ``$1``, ``$2``, etc. in the alias definition
 are expanded by Mercurial before execution. Positional arguments not
 already used by ``$N`` in the definition are put at the end of the
 command to be executed.
 
 Alias definitions consist of lines of the form::
 
     <alias> = <command> [<argument>]...
 
 For example, this definition::
 
     latest = log --limit 5
 
 creates a new command ``latest`` that shows only the five most recent
 changesets. You can define subsequent aliases using earlier ones::
 
     stable5 = latest -b stable
 
 .. note::
 
    It is possible to create aliases with the same names as
    existing commands, which will then override the original
    definitions. This is almost always a bad idea!
 
 An alias can start with an exclamation point (``!``) to make it a
 shell alias. A shell alias is executed with the shell and will let you
 run arbitrary commands. As an example, ::
 
    echo = !echo $@
 
 will let you do ``hg echo foo`` to have ``foo`` printed in your
 terminal. A better example might be::
 
    purge = !$HG status --no-status --unknown -0 re: | xargs -0 rm -f
 
 which will make ``hg purge`` delete all unknown files in the
 repository in the same manner as the purge extension.
 
 Positional arguments like ``$1``, ``$2``, etc. in the alias definition
 expand to the command arguments. Unmatched arguments are
 removed. ``$0`` expands to the alias name and ``$@`` expands to all
 arguments separated by a space. ``"$@"`` (with quotes) expands to all
 arguments quoted individually and separated by a space. These expansions
 happen before the command is passed to the shell.
 
 Shell aliases are executed in an environment where ``$HG`` expands to
 the path of the Mercurial that was used to execute the alias. This is
 useful when you want to call further Mercurial commands in a shell
 alias, as was done above for the purge alias. In addition,
 ``$HG_ARGS`` expands to the arguments given to Mercurial. In the ``hg
 echo foo`` call above, ``$HG_ARGS`` would expand to ``echo foo``.
 
 .. note::
 
    Some global configuration options such as ``-R`` are
    processed before shell aliases and will thus not be passed to
    aliases.
 
 
 ``annotate``
 ------------
 
 Settings used when displaying file annotations. All values are
 Booleans and default to False. See :hg:`help config.diff` for
 related options for the diff command.
 
 ``ignorews``
     Ignore white space when comparing lines.
 
 ``ignorewseol``
     Ignore white space at the end of a line when comparing lines.
 
 ``ignorewsamount``
     Ignore changes in the amount of white space.
 
 ``ignoreblanklines``
     Ignore changes whose lines are all blank.
 
 
 ``auth``
 --------
 
 Authentication credentials and other authentication-like configuration
 for HTTP connections. This section allows you to store usernames and
 passwords for use when logging *into* HTTP servers. See
 :hg:`help config.web` if you want to configure *who* can login to
 your HTTP server.
 
 The following options apply to all hosts.
 
 ``cookiefile``
     Path to a file containing HTTP cookie lines. Cookies matching a
     host will be sent automatically.
 
     The file format uses the Mozilla cookies.txt format, which defines cookies
     on their own lines. Each line contains 7 fields delimited by the tab
     character (domain, is_domain_cookie, path, is_secure, expires, name,
     value). For more info, do an Internet search for "Netscape cookies.txt
     format."
 
     Note: the cookies parser does not handle port numbers on domains. You
     will need to remove ports from the domain for the cookie to be recognized.
     This could result in a cookie being disclosed to an unwanted server.
 
     The cookies file is read-only.
 
 Other options in this section are grouped by name and have the following
 format::
 
     <name>.<argument> = <value>
 
 where ``<name>`` is used to group arguments into authentication
 entries. Example::
 
     foo.prefix = hg.intevation.de/mercurial
     foo.username = foo
     foo.password = bar
     foo.schemes = http https
 
     bar.prefix = secure.example.org
     bar.key = path/to/file.key
     bar.cert = path/to/file.cert
     bar.schemes = https
 
 Supported arguments:
 
 ``prefix``
     Either ``*`` or a URI prefix with or without the scheme part.
     The authentication entry with the longest matching prefix is used
     (where ``*`` matches everything and counts as a match of length
     1). If the prefix doesn't include a scheme, the match is performed
     against the URI with its scheme stripped as well, and the schemes
     argument, q.v., is then subsequently consulted.
 
 ``username``
     Optional. Username to authenticate with. If not given, and the
     remote site requires basic or digest authentication, the user will
     be prompted for it. Environment variables are expanded in the
     username letting you do ``foo.username = $USER``. If the URI
     includes a username, only ``[auth]`` entries with a matching
     username or without a username will be considered.
 
 ``password``
     Optional. Password to authenticate with. If not given, and the
     remote site requires basic or digest authentication, the user
     will be prompted for it.
 
 ``key``
     Optional. PEM encoded client certificate key file. Environment
     variables are expanded in the filename.
 
 ``cert``
     Optional. PEM encoded client certificate chain file. Environment
     variables are expanded in the filename.
 
 ``schemes``
     Optional. Space separated list of URI schemes to use this
     authentication entry with. Only used if the prefix doesn't include
     a scheme. Supported schemes are http and https. They will match
     static-http and static-https respectively, as well.
     (default: https)
 
 If no suitable authentication entry is found, the user is prompted
 for credentials as usual if required by the remote.
 
 ``cmdserver``
 -------------
 
 Controls command server settings. (ADVANCED)
 
 ``message-encodings``
     List of encodings for the ``m`` (message) channel. The first encoding
     supported by the server will be selected and advertised in the hello
     message. This is useful only when ``ui.message-output`` is set to
     ``channel``. Supported encodings are ``cbor``.
 
 ``shutdown-on-interrupt``
     If set to false, the server's main loop will continue running after
     SIGINT received. ``runcommand`` requests can still be interrupted by
     SIGINT. Close the write end of the pipe to shut down the server
     process gracefully.
     (default: True)
 
 ``color``
 ---------
 
 Configure the Mercurial color mode. For details about how to define your custom
 effect and style see :hg:`help color`.
 
 ``mode``
     String: control the method used to output color. One of ``auto``, ``ansi``,
     ``win32``, ``terminfo`` or ``debug``. In auto mode, Mercurial will
     use ANSI mode by default (or win32 mode prior to Windows 10) if it detects a
     terminal. Any invalid value will disable color.
 
 ``pagermode``
     String: optional override of ``color.mode`` used with pager.
 
     On some systems, terminfo mode may cause problems when using
     color with ``less -R`` as a pager program. less with the -R option
     will only display ECMA-48 color codes, and terminfo mode may sometimes
     emit codes that less doesn't understand. You can work around this by
     either using ansi mode (or auto mode), or by using less -r (which will
     pass through all terminal control codes, not just color control
     codes).
 
     On some systems (such as MSYS in Windows), the terminal may support
     a different color mode than the pager program.
 
 ``commands``
 ------------
 
 ``commit.post-status``
     Show status of files in the working directory after successful commit.
     (default: False)
 
 ``merge.require-rev``
     Require that the revision to merge the current commit with be specified on
     the command line. If this is enabled and a revision is not specified, the
     command aborts.
     (default: False)
 
 ``push.require-revs``
     Require revisions to push be specified using one or more mechanisms such as
     specifying them positionally on the command line, using ``-r``, ``-b``,
     and/or ``-B`` on the command line, or using ``paths.<path>:pushrev`` in the
     configuration. If this is enabled and revisions are not specified, the
     command aborts.
     (default: False)
 
 ``resolve.confirm``
     Confirm before performing action if no filename is passed.
     (default: False)
 
 ``resolve.explicit-re-merge``
     Require uses of ``hg resolve`` to specify which action it should perform,
     instead of re-merging files by default.
     (default: False)
 
 ``resolve.mark-check``
     Determines what level of checking :hg:`resolve --mark` will perform before
     marking files as resolved. Valid values are ``none`, ``warn``, and
     ``abort``. ``warn`` will output a warning listing the file(s) that still
     have conflict markers in them, but will still mark everything resolved.
     ``abort`` will output the same warning but will not mark things as resolved.
     If --all is passed and this is set to ``abort``, only a warning will be
     shown (an error will not be raised).
     (default: ``none``)
 
 ``status.relative``
     Make paths in :hg:`status` output relative to the current directory.
     (default: False)
 
 ``status.terse``
     Default value for the --terse flag, which condenses status output.
     (default: empty)
 
 ``update.check``
     Determines what level of checking :hg:`update` will perform before moving
     to a destination revision. Valid values are ``abort``, ``none``,
     ``linear``, and ``noconflict``.
 
     - ``abort`` always fails if the working directory has uncommitted changes.
 
     - ``none`` performs no checking, and may result in a merge with uncommitted changes.
 
     - ``linear`` allows any update as long as it follows a straight line in the
       revision history, and may trigger a merge with uncommitted changes.
 
     - ``noconflict`` will allow any update which would not trigger a merge with
       uncommitted changes, if any are present.
 
     (default: ``linear``)
 
 ``update.requiredest``
     Require that the user pass a destination when running :hg:`update`.
     For example, :hg:`update .::` will be allowed, but a plain :hg:`update`
     will be disallowed.
     (default: False)
 
 ``committemplate``
 ------------------
 
 ``changeset``
     String: configuration in this section is used as the template to
     customize the text shown in the editor when committing.
 
 In addition to pre-defined template keywords, commit log specific one
 below can be used for customization:
 
 ``extramsg``
     String: Extra message (typically 'Leave message empty to abort
     commit.'). This may be changed by some commands or extensions.
 
 For example, the template configuration below shows as same text as
 one shown by default::
 
     [committemplate]
     changeset = {desc}\n\n
         HG: Enter commit message.  Lines beginning with 'HG:' are removed.
         HG: {extramsg}
         HG: --
         HG: user: {author}\n{ifeq(p2rev, "-1", "",
        "HG: branch merge\n")
        }HG: branch '{branch}'\n{if(activebookmark,
        "HG: bookmark '{activebookmark}'\n")   }{subrepos %
        "HG: subrepo {subrepo}\n"              }{file_adds %
        "HG: added {file}\n"                   }{file_mods %
        "HG: changed {file}\n"                 }{file_dels %
        "HG: removed {file}\n"                 }{if(files, "",
        "HG: no files changed\n")}
 
 ``diff()``
     String: show the diff (see :hg:`help templates` for detail)
 
 Sometimes it is helpful to show the diff of the changeset in the editor without
 having to prefix 'HG: ' to each line so that highlighting works correctly. For
 this, Mercurial provides a special string which will ignore everything below
 it::
 
      HG: ------------------------ >8 ------------------------
 
 For example, the template configuration below will show the diff below the
 extra message::
 
     [committemplate]
     changeset = {desc}\n\n
         HG: Enter commit message.  Lines beginning with 'HG:' are removed.
         HG: {extramsg}
         HG: ------------------------ >8 ------------------------
         HG: Do not touch the line above.
         HG: Everything below will be removed.
         {diff()}
 
 .. note::
 
    For some problematic encodings (see :hg:`help win32mbcs` for
    detail), this customization should be configured carefully, to
    avoid showing broken characters.
 
    For example, if a multibyte character ending with backslash (0x5c) is
    followed by the ASCII character 'n' in the customized template,
    the sequence of backslash and 'n' is treated as line-feed unexpectedly
    (and the multibyte character is broken, too).
 
 Customized template is used for commands below (``--edit`` may be
 required):
 
 - :hg:`backout`
 - :hg:`commit`
 - :hg:`fetch` (for merge commit only)
 - :hg:`graft`
 - :hg:`histedit`
 - :hg:`import`
 - :hg:`qfold`, :hg:`qnew` and :hg:`qrefresh`
 - :hg:`rebase`
 - :hg:`shelve`
 - :hg:`sign`
 - :hg:`tag`
 - :hg:`transplant`
 
 Configuring items below instead of ``changeset`` allows showing
 customized message only for specific actions, or showing different
 messages for each action.
 
 - ``changeset.backout`` for :hg:`backout`
 - ``changeset.commit.amend.merge`` for :hg:`commit --amend` on merges
 - ``changeset.commit.amend.normal`` for :hg:`commit --amend` on other
 - ``changeset.commit.normal.merge`` for :hg:`commit` on merges
 - ``changeset.commit.normal.normal`` for :hg:`commit` on other
 - ``changeset.fetch`` for :hg:`fetch` (impling merge commit)
 - ``changeset.gpg.sign`` for :hg:`sign`
 - ``changeset.graft`` for :hg:`graft`
 - ``changeset.histedit.edit`` for ``edit`` of :hg:`histedit`
 - ``changeset.histedit.fold`` for ``fold`` of :hg:`histedit`
 - ``changeset.histedit.mess`` for ``mess`` of :hg:`histedit`
 - ``changeset.histedit.pick`` for ``pick`` of :hg:`histedit`
 - ``changeset.import.bypass`` for :hg:`import --bypass`
 - ``changeset.import.normal.merge`` for :hg:`import` on merges
 - ``changeset.import.normal.normal`` for :hg:`import` on other
 - ``changeset.mq.qnew`` for :hg:`qnew`
 - ``changeset.mq.qfold`` for :hg:`qfold`
 - ``changeset.mq.qrefresh`` for :hg:`qrefresh`
 - ``changeset.rebase.collapse`` for :hg:`rebase --collapse`
 - ``changeset.rebase.merge`` for :hg:`rebase` on merges
 - ``changeset.rebase.normal`` for :hg:`rebase` on other
 - ``changeset.shelve.shelve`` for :hg:`shelve`
 - ``changeset.tag.add`` for :hg:`tag` without ``--remove``
 - ``changeset.tag.remove`` for :hg:`tag --remove`
 - ``changeset.transplant.merge`` for :hg:`transplant` on merges
 - ``changeset.transplant.normal`` for :hg:`transplant` on other
 
 These dot-separated lists of names are treated as hierarchical ones.
 For example, ``changeset.tag.remove`` customizes the commit message
 only for :hg:`tag --remove`, but ``changeset.tag`` customizes the
 commit message for :hg:`tag` regardless of ``--remove`` option.
 
 When the external editor is invoked for a commit, the corresponding
 dot-separated list of names without the ``changeset.`` prefix
 (e.g. ``commit.normal.normal``) is in the ``HGEDITFORM`` environment
 variable.
 
 In this section, items other than ``changeset`` can be referred from
 others. For example, the configuration to list committed files up
 below can be referred as ``{listupfiles}``::
 
     [committemplate]
     listupfiles = {file_adds %
        "HG: added {file}\n"     }{file_mods %
        "HG: changed {file}\n"   }{file_dels %
        "HG: removed {file}\n"   }{if(files, "",
        "HG: no files changed\n")}
 
 ``decode/encode``
 -----------------
 
 Filters for transforming files on checkout/checkin. This would
 typically be used for newline processing or other
 localization/canonicalization of files.
 
 Filters consist of a filter pattern followed by a filter command.
 Filter patterns are globs by default, rooted at the repository root.
 For example, to match any file ending in ``.txt`` in the root
 directory only, use the pattern ``*.txt``. To match any file ending
 in ``.c`` anywhere in the repository, use the pattern ``**.c``.
 For each file only the first matching filter applies.
 
 The filter command can start with a specifier, either ``pipe:`` or
 ``tempfile:``. If no specifier is given, ``pipe:`` is used by default.
 
 A ``pipe:`` command must accept data on stdin and return the transformed
 data on stdout.
 
 Pipe example::
 
   [encode]
   # uncompress gzip files on checkin to improve delta compression
   # note: not necessarily a good idea, just an example
   *.gz = pipe: gunzip
 
   [decode]
   # recompress gzip files when writing them to the working dir (we
   # can safely omit "pipe:", because it's the default)
   *.gz = gzip
 
 A ``tempfile:`` command is a template. The string ``INFILE`` is replaced
 with the name of a temporary file that contains the data to be
 filtered by the command. The string ``OUTFILE`` is replaced with the name
 of an empty temporary file, where the filtered data must be written by
 the command.
 
 .. container:: windows
 
    .. note::
 
      The tempfile mechanism is recommended for Windows systems,
      where the standard shell I/O redirection operators often have
      strange effects and may corrupt the contents of your files.
 
 This filter mechanism is used internally by the ``eol`` extension to
 translate line ending characters between Windows (CRLF) and Unix (LF)
 format. We suggest you use the ``eol`` extension for convenience.
 
 
 ``defaults``
 ------------
 
 (defaults are deprecated. Don't use them. Use aliases instead.)
 
 Use the ``[defaults]`` section to define command defaults, i.e. the
 default options/arguments to pass to the specified commands.
 
 The following example makes :hg:`log` run in verbose mode, and
 :hg:`status` show only the modified files, by default::
 
   [defaults]
   log = -v
   status = -m
 
 The actual commands, instead of their aliases, must be used when
 defining command defaults. The command defaults will also be applied
 to the aliases of the commands defined.
 
 
 ``diff``
 --------
 
 Settings used when displaying diffs. Everything except for ``unified``
 is a Boolean and defaults to False. See :hg:`help config.annotate`
 for related options for the annotate command.
 
 ``git``
     Use git extended diff format.
 
 ``nobinary``
     Omit git binary patches.
 
 ``nodates``
     Don't include dates in diff headers.
 
 ``noprefix``
     Omit 'a/' and 'b/' prefixes from filenames. Ignored in plain mode.
 
 ``showfunc``
     Show which function each change is in.
 
 ``ignorews``
     Ignore white space when comparing lines.
 
 ``ignorewsamount``
     Ignore changes in the amount of white space.
 
 ``ignoreblanklines``
     Ignore changes whose lines are all blank.
 
 ``unified``
     Number of lines of context to show.
 
 ``word-diff``
     Highlight changed words.
 
 ``email``
 ---------
 
 Settings for extensions that send email messages.
 
 ``from``
     Optional. Email address to use in "From" header and SMTP envelope
     of outgoing messages.
 
 ``to``
     Optional. Comma-separated list of recipients' email addresses.
 
 ``cc``
     Optional. Comma-separated list of carbon copy recipients'
     email addresses.
 
 ``bcc``
     Optional. Comma-separated list of blind carbon copy recipients'
     email addresses.
 
 ``method``
     Optional. Method to use to send email messages. If value is ``smtp``
     (default), use SMTP (see the ``[smtp]`` section for configuration).
     Otherwise, use as name of program to run that acts like sendmail
     (takes ``-f`` option for sender, list of recipients on command line,
     message on stdin). Normally, setting this to ``sendmail`` or
     ``/usr/sbin/sendmail`` is enough to use sendmail to send messages.
 
 ``charsets``
     Optional. Comma-separated list of character sets considered
     convenient for recipients. Addresses, headers, and parts not
     containing patches of outgoing messages will be encoded in the
     first character set to which conversion from local encoding
     (``$HGENCODING``, ``ui.fallbackencoding``) succeeds. If correct
     conversion fails, the text in question is sent as is.
     (default: '')
 
     Order of outgoing email character sets:
 
     1. ``us-ascii``: always first, regardless of settings
     2. ``email.charsets``: in order given by user
     3. ``ui.fallbackencoding``: if not in email.charsets
     4. ``$HGENCODING``: if not in email.charsets
     5. ``utf-8``: always last, regardless of settings
 
 Email example::
 
   [email]
   from = Joseph User <[e-mail]>
   method = /usr/sbin/sendmail
   # charsets for western Europeans
   # us-ascii, utf-8 omitted, as they are tried first and last
   charsets = iso-8859-1, iso-8859-15, windows-1252
 
 
 ``extensions``
 --------------
 
 Mercurial has an extension mechanism for adding new features. To
 enable an extension, create an entry for it in this section.
 
 If you know that the extension is already in Python's search path,
 you can give the name of the module, followed by ``=``, with nothing
 after the ``=``.
 
 Otherwise, give a name that you choose, followed by ``=``, followed by
 the path to the ``.py`` file (including the file name extension) that
 defines the extension.
 
 To explicitly disable an extension that is enabled in an hgrc of
 broader scope, prepend its path with ``!``, as in ``foo = !/ext/path``
 or ``foo = !`` when path is not supplied.
 
 Example for ``~/.hgrc``::
 
   [extensions]
   # (the churn extension will get loaded from Mercurial's path)
   churn =
   # (this extension will get loaded from the file specified)
   myfeature = ~/.hgext/myfeature.py
 
 If an extension fails to load, a warning will be issued, and Mercurial will
 proceed. To enforce that an extension must be loaded, one can set the `required`
 suboption in the config::
 
   [extensions]
   myfeature = ~/.hgext/myfeature.py
   myfeature:required = yes
 
 To debug extension loading issue, one can add `--traceback` to their mercurial
 invocation.
 
 A default setting can we set using the special `*` extension key::
 
   [extensions]
   *:required = yes
   myfeature = ~/.hgext/myfeature.py
   rebase=
 
 
 ``format``
 ----------
 
 Configuration that controls the repository format. Newer format options are more
 powerful, but incompatible with some older versions of Mercurial. Format options
 are considered at repository initialization only. You need to make a new clone
 for config changes to be taken into account.
 
 For more details about repository format and version compatibility, see
 https://www.mercurial-scm.org/wiki/MissingRequirement
 
 ``usegeneraldelta``
     Enable or disable the "generaldelta" repository format which improves
     repository compression by allowing "revlog" to store deltas against
     arbitrary revisions instead of the previously stored one. This provides
     significant improvement for repositories with branches.
 
     Repositories with this on-disk format require Mercurial version 1.9.
 
     Enabled by default.
 
 ``dotencode``
     Enable or disable the "dotencode" repository format which enhances
     the "fncache" repository format (which has to be enabled to use
     dotencode) to avoid issues with filenames starting with "._" on
     Mac OS X and spaces on Windows.
 
     Repositories with this on-disk format require Mercurial version 1.7.
 
     Enabled by default.
 
 ``usefncache``
     Enable or disable the "fncache" repository format which enhances
     the "store" repository format (which has to be enabled to use
     fncache) to allow longer filenames and avoids using Windows
     reserved names, e.g. "nul".
 
     Repositories with this on-disk format require Mercurial version 1.1.
 
     Enabled by default.
 
 ``use-dirstate-v2``
     Enable or disable the experimental "dirstate-v2" feature. The dirstate
     functionality is shared by all commands interacting with the working copy.
     The new version is more robust, faster and stores more information.
 
     The performance-improving version of this feature is currently only
     implemented in Rust (see :hg:`help rust`), so people not using a version of
     Mercurial compiled with the Rust parts might actually suffer some slowdown.
     For this reason, such versions will by default refuse to access repositories
     with "dirstate-v2" enabled.
 
     This behavior can be adjusted via configuration: check
     :hg:`help config.storage.dirstate-v2.slow-path` for details.
 
     Repositories with this on-disk format require Mercurial 6.0 or above.
 
     By default this format variant is disabled if the fast implementation is not
     available, and enabled by default if the fast implementation is available.
 
     To accomodate installations of Mercurial without the fast implementation,
     you can downgrade your repository. To do so run the following command:
 
     $ hg debugupgraderepo \
           --run \
           --config format.use-dirstate-v2=False \
           --config storage.dirstate-v2.slow-path=allow
 
     For a more comprehensive guide, see :hg:`help internals.dirstate-v2`.
 
 ``use-dirstate-v2.automatic-upgrade-of-mismatching-repositories``
    When enabled, an automatic upgrade will be triggered when a repository format
    does not match its `use-dirstate-v2` config.
 
    This is an advanced behavior that most users will not need. We recommend you
    don't use this unless you are a seasoned administrator of a Mercurial install
    base.
 
    Automatic upgrade means that any process accessing the repository will
    upgrade the repository format to use `dirstate-v2`. This only triggers if a
    change is needed. This also applies to operations that would have been
    read-only (like hg status).
 
    If the repository cannot be locked, the automatic-upgrade operation will be
    skipped. The next operation will attempt it again.
 
    This configuration will apply for moves in any direction, either adding the
    `dirstate-v2` format if `format.use-dirstate-v2=yes` or removing the
    `dirstate-v2` requirement if `format.use-dirstate-v2=no`. So we recommend
    setting both this value and `format.use-dirstate-v2` at the same time.
 
 ``use-dirstate-v2.automatic-upgrade-of-mismatching-repositories:quiet``
     Hide message when performing such automatic upgrade.
 
 ``use-dirstate-tracked-hint``
     Enable or disable the writing of "tracked key" file alongside the dirstate.
     (default to disabled)
 
     That "tracked-hint" can help external automations to detect changes to the
     set of tracked files. (i.e the result of `hg files` or `hg status -macd`)
 
     The tracked-hint is written in a new `.hg/dirstate-tracked-hint`. That file
     contains two lines:
     - the first line is the file version (currently: 1),
     - the second line contains the "tracked-hint".
     That file is written right after the dirstate is written.
 
     The tracked-hint changes whenever the set of file tracked in the dirstate
     changes. The general idea is:
     - if the hint is identical, the set of tracked file SHOULD be identical,
     - if the hint is different, the set of tracked file MIGHT be different.
 
     The "hint is identical" case uses `SHOULD` as the dirstate and the hint file
     are two distinct files and therefore that cannot be read or written to in an
     atomic way. If the key is identical, nothing garantees that the dirstate is
     not updated right after the hint file. This is considered a negligible
     limitation for the intended usecase. It is actually possible to prevent this
     race by taking the repository lock during read operations.
 
     They are two "ways" to use this feature:
 
     1) monitoring changes to the `.hg/dirstate-tracked-hint`, if the file
     changes, the tracked set might have changed.
 
     2) storing the value and comparing it to a later value.
 
 
 ``use-dirstate-tracked-hint.automatic-upgrade-of-mismatching-repositories``
    When enabled, an automatic upgrade will be triggered when a repository format
    does not match its `use-dirstate-tracked-hint` config.
 
    This is an advanced behavior that most users will not need. We recommend you
    don't use this unless you are a seasoned administrator of a Mercurial install
    base.
 
    Automatic upgrade means that any process accessing the repository will
    upgrade the repository format to use `dirstate-tracked-hint`. This only
    triggers if a change is needed. This also applies to operations that would
    have been read-only (like hg status).
 
    If the repository cannot be locked, the automatic-upgrade operation will be
    skipped. The next operation will attempt it again.
 
    This configuration will apply for moves in any direction, either adding the
    `dirstate-tracked-hint` format if `format.use-dirstate-tracked-hint=yes` or
    removing the `dirstate-tracked-hint` requirement if
    `format.use-dirstate-tracked-hint=no`. So we recommend setting both this
    value and `format.use-dirstate-tracked-hint` at the same time.
 
 
 ``use-dirstate-tracked-hint.automatic-upgrade-of-mismatching-repositories:quiet``
     Hide message when performing such automatic upgrade.
 
 
 ``use-persistent-nodemap``
     Enable or disable the "persistent-nodemap" feature which improves
     performance if the Rust extensions are available.
 
     The "persistent-nodemap" persist the "node -> rev" on disk removing the
     need to dynamically build that mapping for each Mercurial invocation. This
     significantly reduces the startup cost of various local and server-side
     operation for larger repositories.
 
     The performance-improving version of this feature is currently only
     implemented in Rust (see :hg:`help rust`), so people not using a version of
     Mercurial compiled with the Rust parts might actually suffer some slowdown.
     For this reason, such versions will by default refuse to access repositories
     with "persistent-nodemap".
 
     This behavior can be adjusted via configuration: check
     :hg:`help config.storage.revlog.persistent-nodemap.slow-path` for details.
 
     Repositories with this on-disk format require Mercurial 5.4 or above.
 
     By default this format variant is disabled if the fast implementation is not
     available, and enabled by default if the fast implementation is available.
 
     To accomodate installations of Mercurial without the fast implementation,
     you can downgrade your repository. To do so run the following command:
 
     $ hg debugupgraderepo \
           --run \
           --config format.use-persistent-nodemap=False \
           --config storage.revlog.persistent-nodemap.slow-path=allow
 
 ``use-share-safe``
     Enforce "safe" behaviors for all "shares" that access this repository.
 
     With this feature, "shares" using this repository as a source will:
 
     * read the source repository's configuration (`<source>/.hg/hgrc`).
     * read and use the source repository's "requirements"
       (except the working copy specific one).
 
     Without this feature, "shares" using this repository as a source will:
 
     * keep tracking the repository "requirements" in the share only, ignoring
       the source "requirements", possibly diverging from them.
     * ignore source repository config. This can create problems, like silently
       ignoring important hooks.
 
     Beware that existing shares will not be upgraded/downgraded, and by
     default, Mercurial will refuse to interact with them until the mismatch
     is resolved. See :hg:`help config.share.safe-mismatch.source-safe` and
     :hg:`help config.share.safe-mismatch.source-not-safe` for details.
 
     Introduced in Mercurial 5.7.
 
     Enabled by default in Mercurial 6.1.
 
 ``use-share-safe.automatic-upgrade-of-mismatching-repositories``
    When enabled, an automatic upgrade will be triggered when a repository format
    does not match its `use-share-safe` config.
 
    This is an advanced behavior that most users will not need. We recommend you
    don't use this unless you are a seasoned administrator of a Mercurial install
    base.
 
    Automatic upgrade means that any process accessing the repository will
    upgrade the repository format to use `share-safe`. This only triggers if a
    change is needed. This also applies to operation that would have been
    read-only (like hg status).
 
    If the repository cannot be locked, the automatic-upgrade operation will be
    skipped. The next operation will attempt it again.
 
    This configuration will apply for moves in any direction, either adding the
    `share-safe` format if `format.use-share-safe=yes` or removing the
    `share-safe` requirement if `format.use-share-safe=no`. So we recommend
    setting both this value and `format.use-share-safe` at the same time.
 
 ``use-share-safe.automatic-upgrade-of-mismatching-repositories:quiet``
     Hide message when performing such automatic upgrade.
 
 ``usestore``
     Enable or disable the "store" repository format which improves
     compatibility with systems that fold case or otherwise mangle
     filenames. Disabling this option will allow you to store longer filenames
     in some situations at the expense of compatibility.
 
     Repositories with this on-disk format require Mercurial version 0.9.4.
 
     Enabled by default.
 
 ``sparse-revlog``
     Enable or disable the ``sparse-revlog`` delta strategy. This format improves
     delta re-use inside revlog. For very branchy repositories, it results in a
     smaller store. For repositories with many revisions, it also helps
     performance (by using shortened delta chains.)
 
     Repositories with this on-disk format require Mercurial version 4.7
 
     Enabled by default.
 
 ``revlog-compression``
     Compression algorithm used by revlog. Supported values are `zlib` and
     `zstd`. The `zlib` engine is the historical default of Mercurial. `zstd` is
     a newer format that is usually a net win over `zlib`, operating faster at
     better compression rates. Use `zstd` to reduce CPU usage. Multiple values
     can be specified, the first available one will be used.
 
     On some systems, the Mercurial installation may lack `zstd` support.
 
     Default is `zstd` if available, `zlib` otherwise.
 
 ``bookmarks-in-store``
     Store bookmarks in .hg/store/. This means that bookmarks are shared when
     using `hg share` regardless of the `-B` option.
 
     Repositories with this on-disk format require Mercurial version 5.1.
 
     Disabled by default.
 
 
 ``graph``
 ---------
 
 Web graph view configuration. This section let you change graph
 elements display properties by branches, for instance to make the
 ``default`` branch stand out.
 
 Each line has the following format::
 
     <branch>.<argument> = <value>
 
 where ``<branch>`` is the name of the branch being
 customized. Example::
 
     [graph]
     # 2px width
     default.width = 2
     # red color
     default.color = FF0000
 
 Supported arguments:
 
 ``width``
     Set branch edges width in pixels.
 
 ``color``
     Set branch edges color in hexadecimal RGB notation.
 
 ``hooks``
 ---------
 
 Commands or Python functions that get automatically executed by
 various actions such as starting or finishing a commit. Multiple
 hooks can be run for the same action by appending a suffix to the
 action. Overriding a site-wide hook can be done by changing its
 value or setting it to an empty string.  Hooks can be prioritized
 by adding a prefix of ``priority.`` to the hook name on a new line
 and setting the priority. The default priority is 0.
 
 Example ``.hg/hgrc``::
 
   [hooks]
   # update working directory after adding changesets
   changegroup.update = hg update
   # do not use the site-wide hook
   incoming =
   incoming.email = /my/email/hook
   incoming.autobuild = /my/build/hook
   # force autobuild hook to run before other incoming hooks
   priority.incoming.autobuild = 1
   ###  control HGPLAIN setting when running autobuild hook
   # HGPLAIN always set (default from Mercurial 5.7)
   incoming.autobuild:run-with-plain = yes
   # HGPLAIN never set
   incoming.autobuild:run-with-plain = no
   # HGPLAIN inherited from environment (default before Mercurial 5.7)
   incoming.autobuild:run-with-plain = auto
 
 Most hooks are run with environment variables set that give useful
 additional information. For each hook below, the environment variables
 it is passed are listed with names in the form ``$HG_foo``. The
 ``$HG_HOOKTYPE`` and ``$HG_HOOKNAME`` variables are set for all hooks.
 They contain the type of hook which triggered the run and the full name
 of the hook in the config, respectively. In the example above, this will
 be ``$HG_HOOKTYPE=incoming`` and ``$HG_HOOKNAME=incoming.email``.
 
 .. container:: windows
 
   Some basic Unix syntax can be enabled for portability, including ``$VAR``
   and ``${VAR}`` style variables.  A ``~`` followed by ``\`` or ``/`` will
   be expanded to ``%USERPROFILE%`` to simulate a subset of tilde expansion
   on Unix.  To use a literal ``$`` or ``~``, it must be escaped with a back
   slash or inside of a strong quote.  Strong quotes will be replaced by
   double quotes after processing.
 
   This feature is enabled by adding a prefix of ``tonative.`` to the hook
   name on a new line, and setting it to ``True``.  For example::
 
     [hooks]
     incoming.autobuild = /my/build/hook
     # enable translation to cmd.exe syntax for autobuild hook
     tonative.incoming.autobuild = True
 
 ``changegroup``
   Run after a changegroup has been added via push, pull or unbundle.  The ID of
   the first new changeset is in ``$HG_NODE`` and last is in ``$HG_NODE_LAST``.
   The URL from which changes came is in ``$HG_URL``.
 
 ``commit``
   Run after a changeset has been created in the local repository. The ID
   of the newly created changeset is in ``$HG_NODE``. Parent changeset
   IDs are in ``$HG_PARENT1`` and ``$HG_PARENT2``.
 
 ``incoming``
   Run after a changeset has been pulled, pushed, or unbundled into
   the local repository. The ID of the newly arrived changeset is in
   ``$HG_NODE``. The URL that was source of the changes is in ``$HG_URL``.
 
 ``outgoing``
   Run after sending changes from the local repository to another. The ID of
   first changeset sent is in ``$HG_NODE``. The source of operation is in
   ``$HG_SOURCE``. Also see :hg:`help config.hooks.preoutgoing`.
 
 ``post-<command>``
   Run after successful invocations of the associated command. The
   contents of the command line are passed as ``$HG_ARGS`` and the result
   code in ``$HG_RESULT``. Parsed command line arguments are passed as
   ``$HG_PATS`` and ``$HG_OPTS``. These contain string representations of
   the python data internally passed to <command>. ``$HG_OPTS`` is a
   dictionary of options (with unspecified options set to their defaults).
   ``$HG_PATS`` is a list of arguments. Hook failure is ignored.
 
 ``fail-<command>``
   Run after a failed invocation of an associated command. The contents
   of the command line are passed as ``$HG_ARGS``. Parsed command line
   arguments are passed as ``$HG_PATS`` and ``$HG_OPTS``. These contain
   string representations of the python data internally passed to
   <command>. ``$HG_OPTS`` is a dictionary of options (with unspecified
   options set to their defaults). ``$HG_PATS`` is a list of arguments.
   Hook failure is ignored.
 
 ``pre-<command>``
   Run before executing the associated command. The contents of the
   command line are passed as ``$HG_ARGS``. Parsed command line arguments
   are passed as ``$HG_PATS`` and ``$HG_OPTS``. These contain string
   representations of the data internally passed to <command>. ``$HG_OPTS``
   is a dictionary of options (with unspecified options set to their
   defaults). ``$HG_PATS`` is a list of arguments. If the hook returns
   failure, the command doesn't execute and Mercurial returns the failure
   code.
 
 ``prechangegroup``
   Run before a changegroup is added via push, pull or unbundle. Exit
   status 0 allows the changegroup to proceed. A non-zero status will
   cause the push, pull or unbundle to fail. The URL from which changes
   will come is in ``$HG_URL``.
 
 ``precommit``
   Run before starting a local commit. Exit status 0 allows the
   commit to proceed. A non-zero status will cause the commit to fail.
   Parent changeset IDs are in ``$HG_PARENT1`` and ``$HG_PARENT2``.
 
 ``prelistkeys``
   Run before listing pushkeys (like bookmarks) in the
   repository. A non-zero status will cause failure. The key namespace is
   in ``$HG_NAMESPACE``.
 
 ``preoutgoing``
   Run before collecting changes to send from the local repository to
   another. A non-zero status will cause failure. This lets you prevent
   pull over HTTP or SSH. It can also prevent propagating commits (via
   local pull, push (outbound) or bundle commands), but not completely,
   since you can just copy files instead. The source of operation is in
   ``$HG_SOURCE``. If "serve", the operation is happening on behalf of a remote
   SSH or HTTP repository. If "push", "pull" or "bundle", the operation
   is happening on behalf of a repository on same system.
 
 ``prepushkey``
   Run before a pushkey (like a bookmark) is added to the
   repository. A non-zero status will cause the key to be rejected. The
   key namespace is in ``$HG_NAMESPACE``, the key is in ``$HG_KEY``,
   the old value (if any) is in ``$HG_OLD``, and the new value is in
   ``$HG_NEW``.
 
 ``pretag``
   Run before creating a tag. Exit status 0 allows the tag to be
   created. A non-zero status will cause the tag to fail. The ID of the
   changeset to tag is in ``$HG_NODE``. The name of tag is in ``$HG_TAG``. The
   tag is local if ``$HG_LOCAL=1``, or in the repository if ``$HG_LOCAL=0``.
 
 ``pretxnopen``
   Run before any new repository transaction is open. The reason for the
   transaction will be in ``$HG_TXNNAME``, and a unique identifier for the
   transaction will be in ``$HG_TXNID``. A non-zero status will prevent the
   transaction from being opened.
 
 ``pretxnclose``
   Run right before the transaction is actually finalized. Any repository change
   will be visible to the hook program. This lets you validate the transaction
   content or change it. Exit status 0 allows the commit to proceed. A non-zero
   status will cause the transaction to be rolled back. The reason for the
   transaction opening will be in ``$HG_TXNNAME``, and a unique identifier for
   the transaction will be in ``$HG_TXNID``. The rest of the available data will
   vary according the transaction type.  Changes unbundled to the repository will
   add ``$HG_URL`` and ``$HG_SOURCE``.  New changesets will add ``$HG_NODE`` (the
   ID of the first added changeset), ``$HG_NODE_LAST`` (the ID of the last added
   changeset).  Bookmark and phase changes will set ``$HG_BOOKMARK_MOVED`` and
   ``$HG_PHASES_MOVED`` to ``1`` respectively.  The number of new obsmarkers, if
   any, will be in ``$HG_NEW_OBSMARKERS``, etc.
 
 ``pretxnclose-bookmark``
   Run right before a bookmark change is actually finalized. Any repository
   change will be visible to the hook program. This lets you validate the
   transaction content or change it. Exit status 0 allows the commit to
   proceed. A non-zero status will cause the transaction to be rolled back.
   The name of the bookmark will be available in ``$HG_BOOKMARK``, the new
   bookmark location will be available in ``$HG_NODE`` while the previous
   location will be available in ``$HG_OLDNODE``. In case of a bookmark
   creation ``$HG_OLDNODE`` will be empty. In case of deletion ``$HG_NODE``
   will be empty.
   In addition, the reason for the transaction opening will be in
   ``$HG_TXNNAME``, and a unique identifier for the transaction will be in
   ``$HG_TXNID``.
 
 ``pretxnclose-phase``
   Run right before a phase change is actually finalized. Any repository change
   will be visible to the hook program. This lets you validate the transaction
   content or change it. Exit status 0 allows the commit to proceed.  A non-zero
   status will cause the transaction to be rolled back. The hook is called
   multiple times, once for each revision affected by a phase change.
   The affected node is available in ``$HG_NODE``, the phase in ``$HG_PHASE``
   while the previous ``$HG_OLDPHASE``. In case of new node, ``$HG_OLDPHASE``
   will be empty.  In addition, the reason for the transaction opening will be in
   ``$HG_TXNNAME``, and a unique identifier for the transaction will be in
   ``$HG_TXNID``. The hook is also run for newly added revisions. In this case
   the ``$HG_OLDPHASE`` entry will be empty.
 
 ``txnclose``
   Run after any repository transaction has been committed. At this
   point, the transaction can no longer be rolled back. The hook will run
   after the lock is released. See :hg:`help config.hooks.pretxnclose` for
   details about available variables.
 
 ``txnclose-bookmark``
   Run after any bookmark change has been committed. At this point, the
   transaction can no longer be rolled back. The hook will run after the lock
   is released. See :hg:`help config.hooks.pretxnclose-bookmark` for details
   about available variables.
 
 ``txnclose-phase``
   Run after any phase change has been committed. At this point, the
   transaction can no longer be rolled back. The hook will run after the lock
   is released. See :hg:`help config.hooks.pretxnclose-phase` for details about
   available variables.
 
 ``txnabort``
   Run when a transaction is aborted. See :hg:`help config.hooks.pretxnclose`
   for details about available variables.
 
 ``pretxnchangegroup``
   Run after a changegroup has been added via push, pull or unbundle, but before
   the transaction has been committed. The changegroup is visible to the hook
   program. This allows validation of incoming changes before accepting them.
   The ID of the first new changeset is in ``$HG_NODE`` and last is in
   ``$HG_NODE_LAST``. Exit status 0 allows the transaction to commit. A non-zero
   status will cause the transaction to be rolled back, and the push, pull or
   unbundle will fail. The URL that was the source of changes is in ``$HG_URL``.
 
 ``pretxncommit``
   Run after a changeset has been created, but before the transaction is
   committed. The changeset is visible to the hook program. This allows
   validation of the commit message and changes. Exit status 0 allows the
   commit to proceed. A non-zero status will cause the transaction to
   be rolled back. The ID of the new changeset is in ``$HG_NODE``. The parent
   changeset IDs are in ``$HG_PARENT1`` and ``$HG_PARENT2``.
 
 ``preupdate``
   Run before updating the working directory. Exit status 0 allows
   the update to proceed. A non-zero status will prevent the update.
   The changeset ID of first new parent is in ``$HG_PARENT1``. If updating to a
   merge, the ID of second new parent is in ``$HG_PARENT2``.
 
 ``listkeys``
   Run after listing pushkeys (like bookmarks) in the repository. The
   key namespace is in ``$HG_NAMESPACE``. ``$HG_VALUES`` is a
   dictionary containing the keys and values.
 
 ``pushkey``
   Run after a pushkey (like a bookmark) is added to the
   repository. The key namespace is in ``$HG_NAMESPACE``, the key is in
   ``$HG_KEY``, the old value (if any) is in ``$HG_OLD``, and the new
   value is in ``$HG_NEW``.
 
 ``tag``
   Run after a tag is created. The ID of the tagged changeset is in ``$HG_NODE``.
   The name of tag is in ``$HG_TAG``. The tag is local if ``$HG_LOCAL=1``, or in
   the repository if ``$HG_LOCAL=0``.
 
 ``update``
   Run after updating the working directory. The changeset ID of first
   new parent is in ``$HG_PARENT1``. If updating to a merge, the ID of second new
   parent is in ``$HG_PARENT2``. If the update succeeded, ``$HG_ERROR=0``. If the
   update failed (e.g. because conflicts were not resolved), ``$HG_ERROR=1``.
 
 .. note::
 
    It is generally better to use standard hooks rather than the
    generic pre- and post- command hooks, as they are guaranteed to be
    called in the appropriate contexts for influencing transactions.
    Also, hooks like "commit" will be called in all contexts that
    generate a commit (e.g. tag) and not just the commit command.
 
 .. note::
 
    Environment variables with empty values may not be passed to
    hooks on platforms such as Windows. As an example, ``$HG_PARENT2``
    will have an empty value under Unix-like platforms for non-merge
    changesets, while it will not be available at all under Windows.
 
 The syntax for Python hooks is as follows::
 
   hookname = python:modulename.submodule.callable
   hookname = python:/path/to/python/module.py:callable
 
 Python hooks are run within the Mercurial process. Each hook is
 called with at least three keyword arguments: a ui object (keyword
 ``ui``), a repository object (keyword ``repo``), and a ``hooktype``
 keyword that tells what kind of hook is used. Arguments listed as
 environment variables above are passed as keyword arguments, with no
 ``HG_`` prefix, and names in lower case.
 
 If a Python hook returns a "true" value or raises an exception, this
 is treated as a failure.
 
 
 ``hostfingerprints``
 --------------------
 
 (Deprecated. Use ``[hostsecurity]``'s ``fingerprints`` options instead.)
 
 Fingerprints of the certificates of known HTTPS servers.
 
 A HTTPS connection to a server with a fingerprint configured here will
 only succeed if the servers certificate matches the fingerprint.
 This is very similar to how ssh known hosts works.
 
 The fingerprint is the SHA-1 hash value of the DER encoded certificate.
 Multiple values can be specified (separated by spaces or commas). This can
 be used to define both old and new fingerprints while a host transitions
 to a new certificate.
 
 The CA chain and web.cacerts is not used for servers with a fingerprint.
 
 For example::
 
     [hostfingerprints]
     hg.intevation.de = fc:e2:8d:d9:51:cd:cb:c1:4d:18:6b:b7:44:8d:49:72:57:e6:cd:33
     hg.intevation.org = fc:e2:8d:d9:51:cd:cb:c1:4d:18:6b:b7:44:8d:49:72:57:e6:cd:33
 
 ``hostsecurity``
 ----------------
 
 Used to specify global and per-host security settings for connecting to
 other machines.
 
 The following options control default behavior for all hosts.
 
 ``ciphers``
     Defines the cryptographic ciphers to use for connections.
 
     Value must be a valid OpenSSL Cipher List Format as documented at
     https://www.openssl.org/docs/manmaster/apps/ciphers.html#CIPHER-LIST-FORMAT.
 
     This setting is for advanced users only. Setting to incorrect values
     can significantly lower connection security or decrease performance.
     You have been warned.
 
     This option requires Python 2.7.
 
 ``minimumprotocol``
     Defines the minimum channel encryption protocol to use.
 
     By default, the highest version of TLS supported by both client and server
     is used.
 
     Allowed values are: ``tls1.0``, ``tls1.1``, ``tls1.2``.
 
     When running on an old Python version, only ``tls1.0`` is allowed since
     old versions of Python only support up to TLS 1.0.
 
     When running a Python that supports modern TLS versions, the default is
     ``tls1.1``. ``tls1.0`` can still be used to allow TLS 1.0. However, this
     weakens security and should only be used as a feature of last resort if
     a server does not support TLS 1.1+.
 
 Options in the ``[hostsecurity]`` section can have the form
 ``hostname``:``setting``. This allows multiple settings to be defined on a
 per-host basis.
 
 The following per-host settings can be defined.
 
 ``ciphers``
     This behaves like ``ciphers`` as described above except it only applies
     to the host on which it is defined.
 
 ``fingerprints``
     A list of hashes of the DER encoded peer/remote certificate. Values have
     the form ``algorithm``:``fingerprint``. e.g.
     ``sha256:c3ab8ff13720e8ad9047dd39466b3c8974e592c2fa383d4a3960714caef0c4f2``.
     In addition, colons (``:``) can appear in the fingerprint part.
 
     The following algorithms/prefixes are supported: ``sha1``, ``sha256``,
     ``sha512``.
 
     Use of ``sha256`` or ``sha512`` is preferred.
 
     If a fingerprint is specified, the CA chain is not validated for this
     host and Mercurial will require the remote certificate to match one
     of the fingerprints specified. This means if the server updates its
     certificate, Mercurial will abort until a new fingerprint is defined.
     This can provide stronger security than traditional CA-based validation
     at the expense of convenience.
 
     This option takes precedence over ``verifycertsfile``.
 
 ``minimumprotocol``
     This behaves like ``minimumprotocol`` as described above except it
     only applies to the host on which it is defined.
 
 ``verifycertsfile``
     Path to file a containing a list of PEM encoded certificates used to
     verify the server certificate. Environment variables and ``~user``
     constructs are expanded in the filename.
 
     The server certificate or the certificate's certificate authority (CA)
     must match a certificate from this file or certificate verification
     will fail and connections to the server will be refused.
 
     If defined, only certificates provided by this file will be used:
     ``web.cacerts`` and any system/default certificates will not be
     used.
 
     This option has no effect if the per-host ``fingerprints`` option
     is set.
 
     The format of the file is as follows::
 
         -----BEGIN CERTIFICATE-----
         ... (certificate in base64 PEM encoding) ...
         -----END CERTIFICATE-----
         -----BEGIN CERTIFICATE-----
         ... (certificate in base64 PEM encoding) ...
         -----END CERTIFICATE-----
 
 For example::
 
     [hostsecurity]
     hg.example.com:fingerprints = sha256:c3ab8ff13720e8ad9047dd39466b3c8974e592c2fa383d4a3960714caef0c4f2
     hg2.example.com:fingerprints = sha1:914f1aff87249c09b6859b88b1906d30756491ca, sha1:fc:e2:8d:d9:51:cd:cb:c1:4d:18:6b:b7:44:8d:49:72:57:e6:cd:33
     hg3.example.com:fingerprints = sha256:9a:b0:dc:e2:75:ad:8a:b7:84:58:e5:1f:07:32:f1:87:e6:bd:24:22:af:b7:ce:8e:9c:b4:10:cf:b9:f4:0e:d2
     foo.example.com:verifycertsfile = /etc/ssl/trusted-ca-certs.pem
 
 To change the default minimum protocol version to TLS 1.2 but to allow TLS 1.1
 when connecting to ``hg.example.com``::
 
     [hostsecurity]
     minimumprotocol = tls1.2
     hg.example.com:minimumprotocol = tls1.1
 
 ``http_proxy``
 --------------
 
 Used to access web-based Mercurial repositories through a HTTP
 proxy.
 
 ``host``
     Host name and (optional) port of the proxy server, for example
     "myproxy:8000".
 
 ``no``
     Optional. Comma-separated list of host names that should bypass
     the proxy.
 
 ``passwd``
     Optional. Password to authenticate with at the proxy server.
 
 ``user``
     Optional. User name to authenticate with at the proxy server.
 
 ``always``
     Optional. Always use the proxy, even for localhost and any entries
     in ``http_proxy.no``. (default: False)
 
 ``http``
 ----------
 
 Used to configure access to Mercurial repositories via HTTP.
 
 ``timeout``
     If set, blocking operations will timeout after that many seconds.
     (default: None)
 
 ``merge``
 ---------
 
 This section specifies behavior during merges and updates.
 
 ``checkignored``
    Controls behavior when an ignored file on disk has the same name as a tracked
    file in the changeset being merged or updated to, and has different
    contents. Options are ``abort``, ``warn`` and ``ignore``. With ``abort``,
    abort on such files. With ``warn``, warn on such files and back them up as
    ``.orig``. With ``ignore``, don't print a warning and back them up as
    ``.orig``. (default: ``abort``)
 
 ``checkunknown``
    Controls behavior when an unknown file that isn't ignored has the same name
    as a tracked file in the changeset being merged or updated to, and has
    different contents. Similar to ``merge.checkignored``, except for files that
    are not ignored. (default: ``abort``)
 
 ``on-failure``
    When set to ``continue`` (the default), the merge process attempts to
    merge all unresolved files using the merge chosen tool, regardless of
    whether previous file merge attempts during the process succeeded or not.
    Setting this to ``prompt`` will prompt after any merge failure continue
    or halt the merge process. Setting this to ``halt`` will automatically
    halt the merge process on any merge tool failure. The merge process
    can be restarted by using the ``resolve`` command. When a merge is
    halted, the repository is left in a normal ``unresolved`` merge state.
    (default: ``continue``)
 
 ``strict-capability-check``
    Whether capabilities of internal merge tools are checked strictly
    or not, while examining rules to decide merge tool to be used.
    (default: False)
 
 ``merge-patterns``
 ------------------
 
 This section specifies merge tools to associate with particular file
 patterns. Tools matched here will take precedence over the default
 merge tool. Patterns are globs by default, rooted at the repository
 root.
 
 Example::
 
   [merge-patterns]
   **.c = kdiff3
   **.jpg = myimgmerge
 
 ``merge-tools``
 ---------------
 
 This section configures external merge tools to use for file-level
 merges. This section has likely been preconfigured at install time.
 Use :hg:`config merge-tools` to check the existing configuration.
 Also see :hg:`help merge-tools` for more details.
 
 Example ``~/.hgrc``::
 
   [merge-tools]
   # Override stock tool location
   kdiff3.executable = ~/bin/kdiff3
   # Specify command line
   kdiff3.args = $base $local $other -o $output
   # Give higher priority
   kdiff3.priority = 1
 
   # Changing the priority of preconfigured tool
   meld.priority = 0
 
   # Disable a preconfigured tool
   vimdiff.disabled = yes
 
   # Define new tool
   myHtmlTool.args = -m $local $other $base $output
   myHtmlTool.regkey = Software\FooSoftware\HtmlMerge
   myHtmlTool.priority = 1
 
 Supported arguments:
 
 ``priority``
   The priority in which to evaluate this tool.
   (default: 0)
 
 ``executable``
   Either just the name of the executable or its pathname.
 
   .. container:: windows
 
     On Windows, the path can use environment variables with ${ProgramFiles}
     syntax.
 
   (default: the tool name)
 
 ``args``
   The arguments to pass to the tool executable. You can refer to the
   files being merged as well as the output file through these
   variables: ``$base``, ``$local``, ``$other``, ``$output``.
 
   The meaning of ``$local`` and ``$other`` can vary depending on which action is
   being performed. During an update or merge, ``$local`` represents the original
   state of the file, while ``$other`` represents the commit you are updating to or
   the commit you are merging with. During a rebase, ``$local`` represents the
   destination of the rebase, and ``$other`` represents the commit being rebased.
 
   Some operations define custom labels to assist with identifying the revisions,
   accessible via ``$labellocal``, ``$labelother``, and ``$labelbase``. If custom
   labels are not available, these will be ``local``, ``other``, and ``base``,
   respectively.
   (default: ``$local $base $other``)
 
 ``premerge``
   Attempt to run internal non-interactive 3-way merge tool before
   launching external tool.  Options are ``true``, ``false``, ``keep``,
   ``keep-merge3``, or ``keep-mergediff`` (experimental). The ``keep`` option
   will leave markers in the file if the premerge fails. The ``keep-merge3``
   will do the same but include information about the base of the merge in the
   marker (see internal :merge3 in :hg:`help merge-tools`). The
   ``keep-mergediff`` option is similar but uses a different marker style
   (see internal :merge3 in :hg:`help merge-tools`). (default: True)
 
 ``binary``
   This tool can merge binary files. (default: False, unless tool
   was selected by file pattern match)
 
 ``symlink``
   This tool can merge symlinks. (default: False)
 
 ``check``
   A list of merge success-checking options:
 
   ``changed``
     Ask whether merge was successful when the merged file shows no changes.
   ``conflicts``
     Check whether there are conflicts even though the tool reported success.
   ``prompt``
     Always prompt for merge success, regardless of success reported by tool.
 
 ``fixeol``
   Attempt to fix up EOL changes caused by the merge tool.
   (default: False)
 
 ``gui``
   This tool requires a graphical interface to run. (default: False)
 
 ``mergemarkers``
   Controls whether the labels passed via ``$labellocal``, ``$labelother``, and
   ``$labelbase`` are ``detailed`` (respecting ``mergemarkertemplate``) or
   ``basic``. If ``premerge`` is ``keep`` or ``keep-merge3``, the conflict
   markers generated during premerge will be ``detailed`` if either this option or
   the corresponding option in the ``[ui]`` section is ``detailed``.
   (default: ``basic``)
 
 ``mergemarkertemplate``
   This setting can be used to override ``mergemarker`` from the
   ``[command-templates]`` section on a per-tool basis; this applies to the
   ``$label``-prefixed variables and to the conflict markers that are generated
   if ``premerge`` is ``keep` or ``keep-merge3``. See the corresponding variable
   in ``[ui]`` for more information.
 
 .. container:: windows
 
   ``regkey``
     Windows registry key which describes install location of this
     tool. Mercurial will search for this key first under
     ``HKEY_CURRENT_USER`` and then under ``HKEY_LOCAL_MACHINE``.
     (default: None)
 
   ``regkeyalt``
     An alternate Windows registry key to try if the first key is not
     found.  The alternate key uses the same ``regname`` and ``regappend``
     semantics of the primary key.  The most common use for this key
     is to search for 32bit applications on 64bit operating systems.
     (default: None)
 
   ``regname``
     Name of value to read from specified registry key.
     (default: the unnamed (default) value)
 
   ``regappend``
     String to append to the value read from the registry, typically
     the executable name of the tool.
     (default: None)
 
 ``pager``
 ---------
 
 Setting used to control when to paginate and with what external tool. See
 :hg:`help pager` for details.
 
 ``pager``
     Define the external tool used as pager.
 
     If no pager is set, Mercurial uses the environment variable $PAGER.
     If neither pager.pager, nor $PAGER is set, a default pager will be
     used, typically `less` on Unix and `more` on Windows. Example::
 
       [pager]
       pager = less -FRX
 
 ``ignore``
     List of commands to disable the pager for. Example::
 
       [pager]
       ignore = version, help, update
 
 ``patch``
 ---------
 
 Settings used when applying patches, for instance through the 'import'
 command or with Mercurial Queues extension.
 
 ``eol``
     When set to 'strict' patch content and patched files end of lines
     are preserved. When set to ``lf`` or ``crlf``, both files end of
     lines are ignored when patching and the result line endings are
     normalized to either LF (Unix) or CRLF (Windows). When set to
     ``auto``, end of lines are again ignored while patching but line
     endings in patched files are normalized to their original setting
     on a per-file basis. If target file does not exist or has no end
     of line, patch line endings are preserved.
     (default: strict)
 
 ``fuzz``
     The number of lines of 'fuzz' to allow when applying patches. This
     controls how much context the patcher is allowed to ignore when
     trying to apply a patch.
     (default: 2)
 
 ``paths``
 ---------
 
 Assigns symbolic names and behavior to repositories.
 
 Options are symbolic names defining the URL or directory that is the
 location of the repository. Example::
 
     [paths]
     my_server = https://example.com/my_repo
     local_path = /home/me/repo
 
 These symbolic names can be used from the command line. To pull
 from ``my_server``: :hg:`pull my_server`. To push to ``local_path``:
 :hg:`push local_path`. You can check :hg:`help urls` for details about
 valid URLs.
 
 Options containing colons (``:``) denote sub-options that can influence
 behavior for that specific path. Example::
 
     [paths]
     my_server = https://example.com/my_path
     my_server:pushurl = ssh://example.com/my_path
 
 Paths using the `path://otherpath` scheme will inherit the sub-options value from
 the path they point to.
 
 The following sub-options can be defined:
 
 ``multi-urls``
    A boolean option. When enabled the value of the `[paths]` entry will be
    parsed as a list and the alias will resolve to multiple destination. If some
    of the list entry use the `path://` syntax, the suboption will be inherited
    individually.
 
 ``pushurl``
    The URL to use for push operations. If not defined, the location
    defined by the path's main entry is used.
 
 ``pushrev``
    A revset defining which revisions to push by default.
 
    When :hg:`push` is executed without a ``-r`` argument, the revset
    defined by this sub-option is evaluated to determine what to push.
 
    For example, a value of ``.`` will push the working directory's
    revision by default.
 
    Revsets specifying bookmarks will not result in the bookmark being
    pushed.
 
 ``bookmarks.mode``
   How bookmark will be dealt during the exchange. It support the following value
 
   - ``default``: the default behavior, local and remote bookmarks are "merged"
     on push/pull.
 
   - ``mirror``: when pulling, replace local bookmarks by remote bookmarks. This
     is useful to replicate a repository, or as an optimization.
 
   - ``ignore``: ignore bookmarks during exchange.
     (This currently only affect pulling)
 
 The following special named paths exist:
 
 ``default``
    The URL or directory to use when no source or remote is specified.
 
    :hg:`clone` will automatically define this path to the location the
    repository was cloned from.
 
 ``default-push``
    (deprecated) The URL or directory for the default :hg:`push` location.
    ``default:pushurl`` should be used instead.
 
 ``phases``
 ----------
 
 Specifies default handling of phases. See :hg:`help phases` for more
 information about working with phases.
 
 ``publish``
     Controls draft phase behavior when working as a server. When true,
     pushed changesets are set to public in both client and server and
     pulled or cloned changesets are set to public in the client.
     (default: True)
 
 ``new-commit``
     Phase of newly-created commits.
     (default: draft)
 
 ``checksubrepos``
     Check the phase of the current revision of each subrepository. Allowed
     values are "ignore", "follow" and "abort". For settings other than
     "ignore", the phase of the current revision of each subrepository is
     checked before committing the parent repository. If any of those phases is
     greater than the phase of the parent repository (e.g. if a subrepo is in a
     "secret" phase while the parent repo is in "draft" phase), the commit is
     either aborted (if checksubrepos is set to "abort") or the higher phase is
     used for the parent repository commit (if set to "follow").
     (default: follow)
 
 
 ``profiling``
 -------------
 
 Specifies profiling type, format, and file output. Two profilers are
 supported: an instrumenting profiler (named ``ls``), and a sampling
 profiler (named ``stat``).
 
 In this section description, 'profiling data' stands for the raw data
 collected during profiling, while 'profiling report' stands for a
 statistical text report generated from the profiling data.
 
 ``enabled``
     Enable the profiler.
     (default: false)
 
     This is equivalent to passing ``--profile`` on the command line.
 
 ``type``
     The type of profiler to use.
     (default: stat)
 
     ``ls``
       Use Python's built-in instrumenting profiler. This profiler
       works on all platforms, but each line number it reports is the
       first line of a function. This restriction makes it difficult to
       identify the expensive parts of a non-trivial function.
     ``stat``
       Use a statistical profiler, statprof. This profiler is most
       useful for profiling commands that run for longer than about 0.1
       seconds.
 
 ``format``
     Profiling format.  Specific to the ``ls`` instrumenting profiler.
     (default: text)
 
     ``text``
       Generate a profiling report. When saving to a file, it should be
       noted that only the report is saved, and the profiling data is
       not kept.
     ``kcachegrind``
       Format profiling data for kcachegrind use: when saving to a
       file, the generated file can directly be loaded into
       kcachegrind.
 
 ``statformat``
     Profiling format for the ``stat`` profiler.
     (default: hotpath)
 
     ``hotpath``
       Show a tree-based display containing the hot path of execution (where
       most time was spent).
     ``bymethod``
       Show a table of methods ordered by how frequently they are active.
     ``byline``
       Show a table of lines in files ordered by how frequently they are active.
     ``json``
       Render profiling data as JSON.
 
 ``freq``
     Sampling frequency.  Specific to the ``stat`` sampling profiler.
     (default: 1000)
 
 ``output``
     File path where profiling data or report should be saved. If the
     file exists, it is replaced. (default: None, data is printed on
     stderr)
 
 ``sort``
     Sort field.  Specific to the ``ls`` instrumenting profiler.
     One of ``callcount``, ``reccallcount``, ``totaltime`` and
     ``inlinetime``.
     (default: inlinetime)
 
 ``time-track``
     Control if the stat profiler track ``cpu`` or ``real`` time.
     (default: ``cpu`` on Windows, otherwise ``real``)
 
 ``limit``
     Number of lines to show. Specific to the ``ls`` instrumenting profiler.
     (default: 30)
 
 ``nested``
     Show at most this number of lines of drill-down info after each main entry.
     This can help explain the difference between Total and Inline.
     Specific to the ``ls`` instrumenting profiler.
     (default: 0)
 
 ``showmin``
     Minimum fraction of samples an entry must have for it to be displayed.
     Can be specified as a float between ``0.0`` and ``1.0`` or can have a
     ``%`` afterwards to allow values up to ``100``. e.g. ``5%``.
 
     Only used by the ``stat`` profiler.
 
     For the ``hotpath`` format, default is ``0.05``.
     For the ``chrome`` format, default is ``0.005``.
 
     The option is unused on other formats.
 
 ``showmax``
     Maximum fraction of samples an entry can have before it is ignored in
     display. Values format is the same as ``showmin``.
 
     Only used by the ``stat`` profiler.
 
     For the ``chrome`` format, default is ``0.999``.
 
     The option is unused on other formats.
 
 ``showtime``
     Show time taken as absolute durations, in addition to percentages.
     Only used by the ``hotpath`` format.
     (default: true)
 
 ``progress``
 ------------
 
 Mercurial commands can draw progress bars that are as informative as
 possible. Some progress bars only offer indeterminate information, while others
 have a definite end point.
 
 ``debug``
     Whether to print debug info when updating the progress bar. (default: False)
 
 ``delay``
     Number of seconds (float) before showing the progress bar. (default: 3)
 
 ``changedelay``
     Minimum delay before showing a new topic. When set to less than 3 * refresh,
     that value will be used instead. (default: 1)
 
 ``estimateinterval``
     Maximum sampling interval in seconds for speed and estimated time
     calculation. (default: 60)
 
 ``refresh``
     Time in seconds between refreshes of the progress bar. (default: 0.1)
 
 ``format``
     Format of the progress bar.
 
     Valid entries for the format field are ``topic``, ``bar``, ``number``,
     ``unit``, ``estimate``, ``speed``, and ``item``. ``item`` defaults to the
     last 20 characters of the item, but this can be changed by adding either
     ``-<num>`` which would take the last num characters, or ``+<num>`` for the
     first num characters.
 
     (default: topic bar number estimate)
 
 ``width``
     If set, the maximum width of the progress information (that is, min(width,
     term width) will be used).
 
 ``clear-complete``
     Clear the progress bar after it's done. (default: True)
 
 ``disable``
     If true, don't show a progress bar.
 
 ``assume-tty``
     If true, ALWAYS show a progress bar, unless disable is given.
 
 ``rebase``
 ----------
 
 ``evolution.allowdivergence``
     Default to False, when True allow creating divergence when performing
     rebase of obsolete changesets.
 
 ``revsetalias``
 ---------------
 
 Alias definitions for revsets. See :hg:`help revsets` for details.
 
 ``rewrite``
 -----------
 
 ``backup-bundle``
     Whether to save stripped changesets to a bundle file. (default: True)
 
 ``update-timestamp``
     If true, updates the date and time of the changeset to current. It is only
     applicable for `hg amend`, `hg commit --amend` and `hg uncommit` in the
     current version.
 
 ``empty-successor``
 
     Control what happens with empty successors that are the result of rewrite
     operations. If set to ``skip``, the successor is not created. If set to
     ``keep``, the empty successor is created and kept.
 
     Currently, only the rebase and absorb commands consider this configuration.
     (EXPERIMENTAL)
 
 ``rhg``
 -------
 
 The pure Rust fast-path for Mercurial. See `rust/README.rst` in the Mercurial repository.
 
 ``fallback-executable``
     Path to the executable to run in a sub-process when falling back to
     another implementation of Mercurial.
 
+``fallback-immediately``
+    Fall back to ``fallback-executable`` as soon as possible, regardless of
+    the `rhg.on-unsupported` configuration. Useful for debugging, for example to
+    bypass `rhg` if the deault `hg` points to `rhg`.
+
+    Note that because this requires loading the configuration, it is possible
+    that `rhg` error out before being able to fall back.
+
 ``ignored-extensions``
     Controls which extensions should be ignored by `rhg`. By default, `rhg`
     triggers the `rhg.on-unsupported` behavior any unsupported extensions.
     Users can disable that behavior when they know that a given extension
     does not need support from `rhg`.
 
     Expects a list of extension names, or ``*`` to ignore all extensions.
 
     Note: ``*:<suboption>`` is also a valid extension name for this
     configuration option.
     As of this writing, the only valid "global" suboption is ``required``.
 
 ``on-unsupported``
     Controls the behavior of `rhg` when detecting unsupported features.
 
     Possible values are `abort` (default), `abort-silent` and `fallback`.
 
     ``abort``
         Print an error message describing what feature is not supported,
         and exit with code 252
 
     ``abort-silent``
         Silently exit with code 252
 
     ``fallback``
         Try running the fallback executable with the same parameters
         (and trace the fallback reason, use `RUST_LOG=trace` to see).
 
 ``share``
 ---------
 
 ``safe-mismatch.source-safe``
     Controls what happens when the shared repository does not use the
     share-safe mechanism but its source repository does.
 
     Possible values are `abort` (default), `allow`, `upgrade-abort` and
     `upgrade-allow`.
 
     ``abort``
         Disallows running any command and aborts
     ``allow``
         Respects the feature presence in the share source
     ``upgrade-abort``
         Tries to upgrade the share to use share-safe; if it fails, aborts
     ``upgrade-allow``
         Tries to upgrade the share; if it fails, continue by
         respecting the share source setting
 
     Check :hg:`help config.format.use-share-safe` for details about the
     share-safe feature.
 
 ``safe-mismatch.source-safe:verbose-upgrade``
     Display a message when upgrading, (default: True)
 
 ``safe-mismatch.source-safe.warn``
     Shows a warning on operations if the shared repository does not use
     share-safe, but the source repository does.
     (default: True)
 
 ``safe-mismatch.source-not-safe``
     Controls what happens when the shared repository uses the share-safe
     mechanism but its source does not.
 
     Possible values are `abort` (default), `allow`, `downgrade-abort` and
     `downgrade-allow`.
 
     ``abort``
         Disallows running any command and aborts
     ``allow``
         Respects the feature presence in the share source
     ``downgrade-abort``
         Tries to downgrade the share to not use share-safe; if it fails, aborts
     ``downgrade-allow``
         Tries to downgrade the share to not use share-safe;
         if it fails, continue by respecting the shared source setting
 
     Check :hg:`help config.format.use-share-safe` for details about the
     share-safe feature.
 
 ``safe-mismatch.source-not-safe:verbose-upgrade``
     Display a message when upgrading, (default: True)
 
 ``safe-mismatch.source-not-safe.warn``
     Shows a warning on operations if the shared repository uses share-safe,
     but the source repository does not.
     (default: True)
 
 ``storage``
 -----------
 
 Control the strategy Mercurial uses internally to store history. Options in this
 category impact performance and repository size.
 
 ``revlog.issue6528.fix-incoming``
     Version 5.8 of Mercurial had a bug leading to altering the parent of file
     revision with copy information (or any other metadata) on exchange. This
     leads to the copy metadata to be overlooked by various internal logic. The
     issue was fixed in Mercurial 5.8.1.
     (See https://bz.mercurial-scm.org/show_bug.cgi?id=6528 for details)
 
     As a result Mercurial is now checking and fixing incoming file revisions to
     make sure there parents are in the right order. This behavior can be
     disabled by setting this option to `no`. This apply to revisions added
     through push, pull, clone and unbundle.
 
     To fix affected revisions that already exist within the repository, one can
     use :hg:`debug-repair-issue-6528`.
 
 ``revlog.optimize-delta-parent-choice``
     When storing a merge revision, both parents will be equally considered as
     a possible delta base. This results in better delta selection and improved
     revlog compression. This option is enabled by default.
 
     Turning this option off can result in large increase of repository size for
     repository with many merges.
 
 ``revlog.persistent-nodemap.mmap``
     Whether to use the Operating System "memory mapping" feature (when
     possible) to access the persistent nodemap data. This improve performance
     and reduce memory pressure.
 
     Default to True.
 
     For details on the "persistent-nodemap" feature, see:
     :hg:`help config.format.use-persistent-nodemap`.
 
 ``revlog.persistent-nodemap.slow-path``
     Control the behavior of Merucrial when using a repository with "persistent"
     nodemap with an installation of Mercurial without a fast implementation for
     the feature:
 
     ``allow``: Silently use the slower implementation to access the repository.
     ``warn``: Warn, but use the slower implementation to access the repository.
     ``abort``: Prevent access to such repositories. (This is the default)
 
     For details on the "persistent-nodemap" feature, see:
     :hg:`help config.format.use-persistent-nodemap`.
 
 ``revlog.reuse-external-delta-parent``
     Control the order in which delta parents are considered when adding new
     revisions from an external source.
     (typically: apply bundle from `hg pull` or `hg push`).
 
     New revisions are usually provided as a delta against other revisions. By
     default, Mercurial will try to reuse this delta first, therefore using the
     same "delta parent" as the source. Directly using delta's from the source
     reduces CPU usage and usually speeds up operation. However, in some case,
     the source might have sub-optimal delta bases and forcing their reevaluation
     is useful. For example, pushes from an old client could have sub-optimal
     delta's parent that the server want to optimize. (lack of general delta, bad
     parents, choice, lack of sparse-revlog, etc).
 
     This option is enabled by default. Turning it off will ensure bad delta
     parent choices from older client do not propagate to this repository, at
     the cost of a small increase in CPU consumption.
 
     Note: this option only control the order in which delta parents are
     considered.  Even when disabled, the existing delta from the source will be
     reused if the same delta parent is selected.
 
 ``revlog.reuse-external-delta``
     Control the reuse of delta from external source.
     (typically: apply bundle from `hg pull` or `hg push`).
 
     New revisions are usually provided as a delta against another revision. By
     default, Mercurial will not recompute the same delta again, trusting
     externally provided deltas. There have been rare cases of small adjustment
     to the diffing algorithm in the past. So in some rare case, recomputing
     delta provided by ancient clients can provides better results. Disabling
     this option means going through a full delta recomputation for all incoming
     revisions. It means a large increase in CPU usage and will slow operations
     down.
 
     This option is enabled by default. When disabled, it also disables the
     related ``storage.revlog.reuse-external-delta-parent`` option.
 
 ``revlog.zlib.level``
     Zlib compression level used when storing data into the repository. Accepted
     Value range from 1 (lowest compression) to 9 (highest compression). Zlib
     default value is 6.
 
 
 ``revlog.zstd.level``
     zstd compression level used when storing data into the repository. Accepted
     Value range from 1 (lowest compression) to 22 (highest compression).
     (default 3)
 
 ``server``
 ----------
 
 Controls generic server settings.
 
 ``bookmarks-pushkey-compat``
     Trigger pushkey hook when being pushed bookmark updates. This config exist
     for compatibility purpose (default to True)
 
     If you use ``pushkey`` and ``pre-pushkey`` hooks to control bookmark
     movement we recommend you migrate them to ``txnclose-bookmark`` and
     ``pretxnclose-bookmark``.
 
 ``compressionengines``
     List of compression engines and their relative priority to advertise
     to clients.
 
     The order of compression engines determines their priority, the first
     having the highest priority. If a compression engine is not listed
     here, it won't be advertised to clients.
 
     If not set (the default), built-in defaults are used. Run
     :hg:`debuginstall` to list available compression engines and their
     default wire protocol priority.
 
     Older Mercurial clients only support zlib compression and this setting
     has no effect for legacy clients.
 
 ``uncompressed``
     Whether to allow clients to clone a repository using the
     uncompressed streaming protocol. This transfers about 40% more
     data than a regular clone, but uses less memory and CPU on both
     server and client. Over a LAN (100 Mbps or better) or a very fast
     WAN, an uncompressed streaming clone is a lot faster (~10x) than a
     regular clone. Over most WAN connections (anything slower than
     about 6 Mbps), uncompressed streaming is slower, because of the
     extra data transfer overhead. This mode will also temporarily hold
     the write lock while determining what data to transfer.
     (default: True)
 
 ``uncompressedallowsecret``
     Whether to allow stream clones when the repository contains secret
     changesets. (default: False)
 
 ``preferuncompressed``
     When set, clients will try to use the uncompressed streaming
     protocol. (default: False)
 
 ``disablefullbundle``
     When set, servers will refuse attempts to do pull-based clones.
     If this option is set, ``preferuncompressed`` and/or clone bundles
     are highly recommended. Partial clones will still be allowed.
     (default: False)
 
 ``streamunbundle``
     When set, servers will apply data sent from the client directly,
     otherwise it will be written to a temporary file first. This option
     effectively prevents concurrent pushes.
 
 ``pullbundle``
     When set, the server will check pullbundles.manifest for bundles
     covering the requested heads and common nodes. The first matching
     entry will be streamed to the client.
 
     For HTTP transport, the stream will still use zlib compression
     for older clients.
 
 ``concurrent-push-mode``
     Level of allowed race condition between two pushing clients.
 
     - 'strict': push is abort if another client touched the repository
       while the push was preparing.
     - 'check-related': push is only aborted if it affects head that got also
       affected while the push was preparing. (default since 5.4)
 
     'check-related' only takes effect for compatible clients (version
     4.3 and later). Older clients will use 'strict'.
 
 ``validate``
     Whether to validate the completeness of pushed changesets by
     checking that all new file revisions specified in manifests are
     present. (default: False)
 
 ``maxhttpheaderlen``
     Instruct HTTP clients not to send request headers longer than this
     many bytes. (default: 1024)
 
 ``bundle1``
     Whether to allow clients to push and pull using the legacy bundle1
     exchange format. (default: True)
 
 ``bundle1gd``
     Like ``bundle1`` but only used if the repository is using the
     *generaldelta* storage format. (default: True)
 
 ``bundle1.push``
     Whether to allow clients to push using the legacy bundle1 exchange
     format. (default: True)
 
 ``bundle1gd.push``
     Like ``bundle1.push`` but only used if the repository is using the
     *generaldelta* storage format. (default: True)
 
 ``bundle1.pull``
     Whether to allow clients to pull using the legacy bundle1 exchange
     format. (default: True)
 
 ``bundle1gd.pull``
     Like ``bundle1.pull`` but only used if the repository is using the
     *generaldelta* storage format. (default: True)
 
     Large repositories using the *generaldelta* storage format should
     consider setting this option because converting *generaldelta*
     repositories to the exchange format required by the bundle1 data
     format can consume a lot of CPU.
 
 ``bundle2.stream``
     Whether to allow clients to pull using the bundle2 streaming protocol.
     (default: True)
 
 ``zliblevel``
     Integer between ``-1`` and ``9`` that controls the zlib compression level
     for wire protocol commands that send zlib compressed output (notably the
     commands that send repository history data).
 
     The default (``-1``) uses the default zlib compression level, which is
     likely equivalent to ``6``. ``0`` means no compression. ``9`` means
     maximum compression.
 
     Setting this option allows server operators to make trade-offs between
     bandwidth and CPU used. Lowering the compression lowers CPU utilization
     but sends more bytes to clients.
 
     This option only impacts the HTTP server.
 
 ``zstdlevel``
     Integer between ``1`` and ``22`` that controls the zstd compression level
     for wire protocol commands. ``1`` is the minimal amount of compression and
     ``22`` is the highest amount of compression.
 
     The default (``3``) should be significantly faster than zlib while likely
     delivering better compression ratios.
 
     This option only impacts the HTTP server.
 
     See also ``server.zliblevel``.
 
 ``view``
     Repository filter used when exchanging revisions with the peer.
 
     The default view (``served``) excludes secret and hidden changesets.
     Another useful value is ``immutable`` (no draft, secret or hidden
     changesets). (EXPERIMENTAL)
 
 ``smtp``
 --------
 
 Configuration for extensions that need to send email messages.
 
 ``host``
     Host name of mail server, e.g. "mail.example.com".
 
 ``port``
     Optional. Port to connect to on mail server. (default: 465 if
     ``tls`` is smtps; 25 otherwise)
 
 ``tls``
     Optional. Method to enable TLS when connecting to mail server: starttls,
     smtps or none. (default: none)
 
 ``username``
     Optional. User name for authenticating with the SMTP server.
     (default: None)
 
 ``password``
     Optional. Password for authenticating with the SMTP server. If not
     specified, interactive sessions will prompt the user for a
     password; non-interactive sessions will fail. (default: None)
 
 ``local_hostname``
     Optional. The hostname that the sender can use to identify
     itself to the MTA.
 
 
 ``subpaths``
 ------------
 
 Subrepository source URLs can go stale if a remote server changes name
 or becomes temporarily unavailable. This section lets you define
 rewrite rules of the form::
 
     <pattern> = <replacement>
 
 where ``pattern`` is a regular expression matching a subrepository
 source URL and ``replacement`` is the replacement string used to
 rewrite it. Groups can be matched in ``pattern`` and referenced in
 ``replacements``. For instance::
 
     http://server/(.*)-hg/ = http://hg.server/\1/
 
 rewrites ``http://server/foo-hg/`` into ``http://hg.server/foo/``.
 
 Relative subrepository paths are first made absolute, and the
 rewrite rules are then applied on the full (absolute) path. If ``pattern``
 doesn't match the full path, an attempt is made to apply it on the
 relative path alone. The rules are applied in definition order.
 
 ``subrepos``
 ------------
 
 This section contains options that control the behavior of the
 subrepositories feature. See also :hg:`help subrepos`.
 
 Security note: auditing in Mercurial is known to be insufficient to
 prevent clone-time code execution with carefully constructed Git
 subrepos. It is unknown if a similar detect is present in Subversion
 subrepos. Both Git and Subversion subrepos are disabled by default
 out of security concerns. These subrepo types can be enabled using
 the respective options below.
 
 ``allowed``
     Whether subrepositories are allowed in the working directory.
 
     When false, commands involving subrepositories (like :hg:`update`)
     will fail for all subrepository types.
     (default: true)
 
 ``hg:allowed``
     Whether Mercurial subrepositories are allowed in the working
     directory. This option only has an effect if ``subrepos.allowed``
     is true.
     (default: true)
 
 ``git:allowed``
     Whether Git subrepositories are allowed in the working directory.
     This option only has an effect if ``subrepos.allowed`` is true.
 
     See the security note above before enabling Git subrepos.
     (default: false)
 
 ``svn:allowed``
     Whether Subversion subrepositories are allowed in the working
     directory. This option only has an effect if ``subrepos.allowed``
     is true.
 
     See the security note above before enabling Subversion subrepos.
     (default: false)
 
 ``templatealias``
 -----------------
 
 Alias definitions for templates. See :hg:`help templates` for details.
 
 ``templates``
 -------------
 
 Use the ``[templates]`` section to define template strings.
 See :hg:`help templates` for details.
 
 ``trusted``
 -----------
 
 Mercurial will not use the settings in the
 ``.hg/hgrc`` file from a repository if it doesn't belong to a trusted
 user or to a trusted group, as various hgrc features allow arbitrary
 commands to be run. This issue is often encountered when configuring
 hooks or extensions for shared repositories or servers. However,
 the web interface will use some safe settings from the ``[web]``
 section.
 
 This section specifies what users and groups are trusted. The
 current user is always trusted. To trust everybody, list a user or a
 group with name ``*``. These settings must be placed in an
 *already-trusted file* to take effect, such as ``$HOME/.hgrc`` of the
 user or service running Mercurial.
 
 ``users``
   Comma-separated list of trusted users.
 
 ``groups``
   Comma-separated list of trusted groups.
 
 
 ``ui``
 ------
 
 User interface controls.
 
 ``archivemeta``
     Whether to include the .hg_archival.txt file containing meta data
     (hashes for the repository base and for tip) in archives created
     by the :hg:`archive` command or downloaded via hgweb.
     (default: True)
 
 ``askusername``
     Whether to prompt for a username when committing. If True, and
     neither ``$HGUSER`` nor ``$EMAIL`` has been specified, then the user will
     be prompted to enter a username. If no username is entered, the
     default ``USER@HOST`` is used instead.
     (default: False)
 
 ``clonebundles``
     Whether the "clone bundles" feature is enabled.
 
     When enabled, :hg:`clone` may download and apply a server-advertised
     bundle file from a URL instead of using the normal exchange mechanism.
 
     This can likely result in faster and more reliable clones.
 
     (default: True)
 
 ``clonebundlefallback``
     Whether failure to apply an advertised "clone bundle" from a server
     should result in fallback to a regular clone.
 
     This is disabled by default because servers advertising "clone
     bundles" often do so to reduce server load. If advertised bundles
     start mass failing and clients automatically fall back to a regular
     clone, this would add significant and unexpected load to the server
     since the server is expecting clone operations to be offloaded to
     pre-generated bundles. Failing fast (the default behavior) ensures
     clients don't overwhelm the server when "clone bundle" application
     fails.
 
     (default: False)
 
 ``clonebundleprefers``
     Defines preferences for which "clone bundles" to use.
 
     Servers advertising "clone bundles" may advertise multiple available
     bundles. Each bundle may have different attributes, such as the bundle
     type and compression format. This option is used to prefer a particular
     bundle over another.
 
     The following keys are defined by Mercurial:
 
     BUNDLESPEC
        A bundle type specifier. These are strings passed to :hg:`bundle -t`.
        e.g. ``gzip-v2`` or ``bzip2-v1``.
 
     COMPRESSION
        The compression format of the bundle. e.g. ``gzip`` and ``bzip2``.
 
     Server operators may define custom keys.
 
     Example values: ``COMPRESSION=bzip2``,
     ``BUNDLESPEC=gzip-v2, COMPRESSION=gzip``.
 
     By default, the first bundle advertised by the server is used.
 
 ``color``
     When to colorize output. Possible value are Boolean ("yes" or "no"), or
     "debug", or "always". (default: "yes"). "yes" will use color whenever it
     seems possible. See :hg:`help color` for details.
 
 ``commitsubrepos``
     Whether to commit modified subrepositories when committing the
     parent repository. If False and one subrepository has uncommitted
     changes, abort the commit.
     (default: False)
 
 ``debug``
     Print debugging information. (default: False)
 
 ``editor``
     The editor to use during a commit. (default: ``$EDITOR`` or ``vi``)
 
 ``fallbackencoding``
     Encoding to try if it's not possible to decode the changelog using
     UTF-8. (default: ISO-8859-1)
 
 ``graphnodetemplate``
     (DEPRECATED) Use ``command-templates.graphnode`` instead.
 
 ``ignore``
     A file to read per-user ignore patterns from. This file should be
     in the same format as a repository-wide .hgignore file. Filenames
     are relative to the repository root. This option supports hook syntax,
     so if you want to specify multiple ignore files, you can do so by
     setting something like ``ignore.other = ~/.hgignore2``. For details
     of the ignore file format, see the ``hgignore(5)`` man page.
 
 ``interactive``
     Allow to prompt the user. (default: True)
 
 ``interface``
     Select the default interface for interactive features (default: text).
     Possible values are 'text' and 'curses'.
 
 ``interface.chunkselector``
     Select the interface for change recording (e.g. :hg:`commit -i`).
     Possible values are 'text' and 'curses'.
     This config overrides the interface specified by ui.interface.
 
 ``large-file-limit``
     Largest file size that gives no memory use warning.
     Possible values are integers or 0 to disable the check.
     Value is expressed in bytes by default, one can use standard units for
     convenience (e.g. 10MB, 0.1GB, etc) (default: 10MB)
 
 ``logtemplate``
     (DEPRECATED) Use ``command-templates.log`` instead.
 
 ``merge``
     The conflict resolution program to use during a manual merge.
     For more information on merge tools see :hg:`help merge-tools`.
     For configuring merge tools see the ``[merge-tools]`` section.
 
 ``mergemarkers``
     Sets the merge conflict marker label styling. The ``detailed`` style
     uses the ``command-templates.mergemarker`` setting to style the labels.
     The ``basic`` style just uses 'local' and 'other' as the marker label.
     One of ``basic`` or ``detailed``.
     (default: ``basic``)
 
 ``mergemarkertemplate``
     (DEPRECATED) Use ``command-templates.mergemarker`` instead.
 
 ``message-output``
     Where to write status and error messages. (default: ``stdio``)
 
     ``channel``
       Use separate channel for structured output. (Command-server only)
     ``stderr``
       Everything to stderr.
     ``stdio``
       Status to stdout, and error to stderr.
 
 ``origbackuppath``
     The path to a directory used to store generated .orig files. If the path is
     not a directory, one will be created.  If set, files stored in this
     directory have the same name as the original file and do not have a .orig
     suffix.
 
 ``paginate``
   Control the pagination of command output (default: True). See :hg:`help pager`
   for details.
 
 ``patch``
     An optional external tool that ``hg import`` and some extensions
     will use for applying patches. By default Mercurial uses an
     internal patch utility. The external tool must work as the common
     Unix ``patch`` program. In particular, it must accept a ``-p``
     argument to strip patch headers, a ``-d`` argument to specify the
     current directory, a file name to patch, and a patch file to take
     from stdin.
 
     It is possible to specify a patch tool together with extra
     arguments. For example, setting this option to ``patch --merge``
     will use the ``patch`` program with its 2-way merge option.
 
 ``portablefilenames``
     Check for portable filenames. Can be ``warn``, ``ignore`` or ``abort``.
     (default: ``warn``)
 
     ``warn``
       Print a warning message on POSIX platforms, if a file with a non-portable
       filename is added (e.g. a file with a name that can't be created on
       Windows because it contains reserved parts like ``AUX``, reserved
       characters like ``:``, or would cause a case collision with an existing
       file).
 
     ``ignore``
       Don't print a warning.
 
     ``abort``
       The command is aborted.
 
     ``true``
       Alias for ``warn``.
 
     ``false``
       Alias for ``ignore``.
 
     .. container:: windows
 
       On Windows, this configuration option is ignored and the command aborted.
 
 ``pre-merge-tool-output-template``
     (DEPRECATED) Use ``command-template.pre-merge-tool-output`` instead.
 
 ``quiet``
     Reduce the amount of output printed.
     (default: False)
 
 ``relative-paths``
     Prefer relative paths in the UI.
 
 ``remotecmd``
     Remote command to use for clone/push/pull operations.
     (default: ``hg``)
 
 ``report_untrusted``
     Warn if a ``.hg/hgrc`` file is ignored due to not being owned by a
     trusted user or group.
     (default: True)
 
 ``slash``
     (Deprecated. Use ``slashpath`` template filter instead.)
 
     Display paths using a slash (``/``) as the path separator. This
     only makes a difference on systems where the default path
     separator is not the slash character (e.g. Windows uses the
     backslash character (``\``)).
     (default: False)
 
 ``statuscopies``
     Display copies in the status command.
 
 ``ssh``
     Command to use for SSH connections. (default: ``ssh``)
 
 ``ssherrorhint``
     A hint shown to the user in the case of SSH error (e.g.
     ``Please see http://company/internalwiki/ssh.html``)
 
 ``strict``
     Require exact command names, instead of allowing unambiguous
     abbreviations. (default: False)
 
 ``style``
     Name of style to use for command output.
 
 ``supportcontact``
     A URL where users should report a Mercurial traceback. Use this if you are a
     large organisation with its own Mercurial deployment process and crash
     reports should be addressed to your internal support.
 
 ``textwidth``
     Maximum width of help text. A longer line generated by ``hg help`` or
     ``hg subcommand --help`` will be broken after white space to get this
     width or the terminal width, whichever comes first.
     A non-positive value will disable this and the terminal width will be
     used. (default: 78)
 
 ``timeout``
     The timeout used when a lock is held (in seconds), a negative value
     means no timeout. (default: 600)
 
 ``timeout.warn``
     Time (in seconds) before a warning is printed about held lock. A negative
     value means no warning. (default: 0)
 
 ``traceback``
     Mercurial always prints a traceback when an unknown exception
     occurs. Setting this to True will make Mercurial print a traceback
     on all exceptions, even those recognized by Mercurial (such as
     IOError or MemoryError). (default: False)
 
 ``tweakdefaults``
 
     By default Mercurial's behavior changes very little from release
     to release, but over time the recommended config settings
     shift. Enable this config to opt in to get automatic tweaks to
     Mercurial's behavior over time. This config setting will have no
     effect if ``HGPLAIN`` is set or ``HGPLAINEXCEPT`` is set and does
     not include ``tweakdefaults``. (default: False)
 
     It currently means::
 
       .. tweakdefaultsmarker
 
 ``username``
     The committer of a changeset created when running "commit".
     Typically a person's name and email address, e.g. ``Fred Widget
     <[e-mail]>``. Environment variables in the
     username are expanded.
 
     (default: ``$EMAIL`` or ``username@hostname``. If the username in
     hgrc is empty, e.g. if the system admin set ``username =`` in the
     system hgrc, it has to be specified manually or in a different
     hgrc file)
 
 ``verbose``
     Increase the amount of output printed. (default: False)
 
 
 ``command-templates``
 ---------------------
 
 Templates used for customizing the output of commands.
 
 ``graphnode``
     The template used to print changeset nodes in an ASCII revision graph.
     (default: ``{graphnode}``)
 
 ``log``
     Template string for commands that print changesets.
 
 ``mergemarker``
     The template used to print the commit description next to each conflict
     marker during merge conflicts. See :hg:`help templates` for the template
     format.
 
     Defaults to showing the hash, tags, branches, bookmarks, author, and
     the first line of the commit description.
 
     If you use non-ASCII characters in names for tags, branches, bookmarks,
     authors, and/or commit descriptions, you must pay attention to encodings of
     managed files. At template expansion, non-ASCII characters use the encoding
     specified by the ``--encoding`` global option, ``HGENCODING`` or other
     environment variables that govern your locale. If the encoding of the merge
     markers is different from the encoding of the merged files,
     serious problems may occur.
 
     Can be overridden per-merge-tool, see the ``[merge-tools]`` section.
 
 ``oneline-summary``
     A template used by `hg rebase` and other commands for showing a one-line
     summary of a commit. If the template configured here is longer than one
     line, then only the first line is used.
 
     The template can be overridden per command by defining a template in
     `oneline-summary.<command>`, where `<command>` can be e.g. "rebase".
 
 ``pre-merge-tool-output``
     A template that is printed before executing an external merge tool. This can
     be used to print out additional context that might be useful to have during
     the conflict resolution, such as the description of the various commits
     involved or bookmarks/tags.
 
     Additional information is available in the ``local`, ``base``, and ``other``
     dicts. For example: ``{local.label}``, ``{base.name}``, or
     ``{other.islink}``.
 
 
 ``web``
 -------
 
 Web interface configuration. The settings in this section apply to
 both the builtin webserver (started by :hg:`serve`) and the script you
 run through a webserver (``hgweb.cgi`` and the derivatives for FastCGI
 and WSGI).
 
 The Mercurial webserver does no authentication (it does not prompt for
 usernames and passwords to validate *who* users are), but it does do
 authorization (it grants or denies access for *authenticated users*
 based on settings in this section). You must either configure your
 webserver to do authentication for you, or disable the authorization
 checks.
 
 For a quick setup in a trusted environment, e.g., a private LAN, where
 you want it to accept pushes from anybody, you can use the following
 command line::
 
     $ hg --config web.allow-push=* --config web.push_ssl=False serve
 
 Note that this will allow anybody to push anything to the server and
 that this should not be used for public servers.
 
 The full set of options is:
 
 ``accesslog``
     Where to output the access log. (default: stdout)
 
 ``address``
     Interface address to bind to. (default: all)
 
 ``allow-archive``
     List of archive format (bz2, gz, zip) allowed for downloading.
     (default: empty)
 
 ``allowbz2``
     (DEPRECATED) Whether to allow .tar.bz2 downloading of repository
     revisions.
     (default: False)
 
 ``allowgz``
     (DEPRECATED) Whether to allow .tar.gz downloading of repository
     revisions.
     (default: False)
 
 ``allow-pull``
     Whether to allow pulling from the repository. (default: True)
 
 ``allow-push``
     Whether to allow pushing to the repository. If empty or not set,
     pushing is not allowed. If the special value ``*``, any remote
     user can push, including unauthenticated users. Otherwise, the
     remote user must have been authenticated, and the authenticated
     user name must be present in this list. The contents of the
     allow-push list are examined after the deny_push list.
 
 ``allow_read``
     If the user has not already been denied repository access due to
     the contents of deny_read, this list determines whether to grant
     repository access to the user. If this list is not empty, and the
     user is unauthenticated or not present in the list, then access is
     denied for the user. If the list is empty or not set, then access
     is permitted to all users by default. Setting allow_read to the
     special value ``*`` is equivalent to it not being set (i.e. access
     is permitted to all users). The contents of the allow_read list are
     examined after the deny_read list.
 
 ``allowzip``
     (DEPRECATED) Whether to allow .zip downloading of repository
     revisions. This feature creates temporary files.
     (default: False)
 
 ``archivesubrepos``
     Whether to recurse into subrepositories when archiving.
     (default: False)
 
 ``baseurl``
     Base URL to use when publishing URLs in other locations, so
     third-party tools like email notification hooks can construct
     URLs. Example: ``http://hgserver/repos/``.
 
 ``cacerts``
     Path to file containing a list of PEM encoded certificate
     authority certificates. Environment variables and ``~user``
     constructs are expanded in the filename. If specified on the
     client, then it will verify the identity of remote HTTPS servers
     with these certificates.
 
     To disable SSL verification temporarily, specify ``--insecure`` from
     command line.
 
     You can use OpenSSL's CA certificate file if your platform has
     one. On most Linux systems this will be
     ``/etc/ssl/certs/ca-certificates.crt``. Otherwise you will have to
     generate this file manually. The form must be as follows::
 
         -----BEGIN CERTIFICATE-----
         ... (certificate in base64 PEM encoding) ...
         -----END CERTIFICATE-----
         -----BEGIN CERTIFICATE-----
         ... (certificate in base64 PEM encoding) ...
         -----END CERTIFICATE-----
 
 ``cache``
     Whether to support caching in hgweb. (default: True)
 
 ``certificate``
     Certificate to use when running :hg:`serve`.
 
 ``collapse``
     With ``descend`` enabled, repositories in subdirectories are shown at
     a single level alongside repositories in the current path. With
     ``collapse`` also enabled, repositories residing at a deeper level than
     the current path are grouped behind navigable directory entries that
     lead to the locations of these repositories. In effect, this setting
     collapses each collection of repositories found within a subdirectory
     into a single entry for that subdirectory. (default: False)
 
 ``comparisoncontext``
     Number of lines of context to show in side-by-side file comparison. If
     negative or the value ``full``, whole files are shown. (default: 5)
 
     This setting can be overridden by a ``context`` request parameter to the
     ``comparison`` command, taking the same values.
 
 ``contact``
     Name or email address of the person in charge of the repository.
     (default: ui.username or ``$EMAIL`` or "unknown" if unset or empty)
 
 ``csp``
     Send a ``Content-Security-Policy`` HTTP header with this value.
 
     The value may contain a special string ``%nonce%``, which will be replaced
     by a randomly-generated one-time use value. If the value contains
     ``%nonce%``, ``web.cache`` will be disabled, as caching undermines the
     one-time property of the nonce. This nonce will also be inserted into
     ``<script>`` elements containing inline JavaScript.
 
     Note: lots of HTML content sent by the server is derived from repository
     data. Please consider the potential for malicious repository data to
     "inject" itself into generated HTML content as part of your security
     threat model.
 
 ``deny_push``
     Whether to deny pushing to the repository. If empty or not set,
     push is not denied. If the special value ``*``, all remote users are
     denied push. Otherwise, unauthenticated users are all denied, and
     any authenticated user name present in this list is also denied. The
     contents of the deny_push list are examined before the allow-push list.
 
 ``deny_read``
     Whether to deny reading/viewing of the repository. If this list is
     not empty, unauthenticated users are all denied, and any
     authenticated user name present in this list is also denied access to
     the repository. If set to the special value ``*``, all remote users
     are denied access (rarely needed ;). If deny_read is empty or not set,
     the determination of repository access depends on the presence and
     content of the allow_read list (see description). If both
     deny_read and allow_read are empty or not set, then access is
     permitted to all users by default. If the repository is being
     served via hgwebdir, denied users will not be able to see it in
     the list of repositories. The contents of the deny_read list have
     priority over (are examined before) the contents of the allow_read
     list.
 
 ``descend``
     hgwebdir indexes will not descend into subdirectories. Only repositories
     directly in the current path will be shown (other repositories are still
     available from the index corresponding to their containing path).
 
 ``description``
     Textual description of the repository's purpose or contents.
     (default: "unknown")
 
 ``encoding``
     Character encoding name. (default: the current locale charset)
     Example: "UTF-8".
 
 ``errorlog``
     Where to output the error log. (default: stderr)
 
 ``guessmime``
     Control MIME types for raw download of file content.
     Set to True to let hgweb guess the content type from the file
     extension. This will serve HTML files as ``text/html`` and might
     allow cross-site scripting attacks when serving untrusted
     repositories. (default: False)
 
 ``hidden``
     Whether to hide the repository in the hgwebdir index.
     (default: False)
 
 ``ipv6``
     Whether to use IPv6. (default: False)
 
 ``labels``
     List of string *labels* associated with the repository.
 
     Labels are exposed as a template keyword and can be used to customize
     output. e.g. the ``index`` template can group or filter repositories
     by labels and the ``summary`` template can display additional content
     if a specific label is present.
 
 ``logoimg``
     File name of the logo image that some templates display on each page.
     The file name is relative to ``staticurl``. That is, the full path to
     the logo image is "staticurl/logoimg".
     If unset, ``hglogo.png`` will be used.
 
 ``logourl``
     Base URL to use for logos. If unset, ``https://mercurial-scm.org/``
     will be used.
 
 ``maxchanges``
     Maximum number of changes to list on the changelog. (default: 10)
 
 ``maxfiles``
     Maximum number of files to list per changeset. (default: 10)
 
 ``maxshortchanges``
     Maximum number of changes to list on the shortlog, graph or filelog
     pages. (default: 60)
 
 ``name``
     Repository name to use in the web interface.
     (default: current working directory)
 
 ``port``
     Port to listen on. (default: 8000)
 
 ``prefix``
     Prefix path to serve from. (default: '' (server root))
 
 ``push_ssl``
     Whether to require that inbound pushes be transported over SSL to
     prevent password sniffing. (default: True)
 
 ``refreshinterval``
     How frequently directory listings re-scan the filesystem for new
     repositories, in seconds. This is relevant when wildcards are used
     to define paths. Depending on how much filesystem traversal is
     required, refreshing may negatively impact performance.
 
     Values less than or equal to 0 always refresh.
     (default: 20)
 
 ``server-header``
     Value for HTTP ``Server`` response header.
 
 ``static``
     Directory where static files are served from.
 
 ``staticurl``
     Base URL to use for static files. If unset, static files (e.g. the
     hgicon.png favicon) will be served by the CGI script itself. Use
     this setting to serve them directly with the HTTP server.
     Example: ``http://hgserver/static/``.
 
 ``stripes``
     How many lines a "zebra stripe" should span in multi-line output.
     Set to 0 to disable. (default: 1)
 
 ``style``
     Which template map style to use. The available options are the names of
     subdirectories in the HTML templates path. (default: ``paper``)
     Example: ``monoblue``.
 
 ``templates``
     Where to find the HTML templates. The default path to the HTML templates
     can be obtained from ``hg debuginstall``.
 
 ``websub``
 ----------
 
 Web substitution filter definition. You can use this section to
 define a set of regular expression substitution patterns which
 let you automatically modify the hgweb server output.
 
 The default hgweb templates only apply these substitution patterns
 on the revision description fields. You can apply them anywhere
 you want when you create your own templates by adding calls to the
 "websub" filter (usually after calling the "escape" filter).
 
 This can be used, for example, to convert issue references to links
 to your issue tracker, or to convert "markdown-like" syntax into
 HTML (see the examples below).
 
 Each entry in this section names a substitution filter.
 The value of each entry defines the substitution expression itself.
 The websub expressions follow the old interhg extension syntax,
 which in turn imitates the Unix sed replacement syntax::
 
     patternname = s/SEARCH_REGEX/REPLACE_EXPRESSION/[i]
 
 You can use any separator other than "/". The final "i" is optional
 and indicates that the search must be case insensitive.
 
 Examples::
 
     [websub]
     issues = s|issue(\d+)|<a href="http://bts.example.org/issue\1">issue\1</a>|i
     italic = s/\b_(\S+)_\b/<i>\1<\/i>/
     bold = s/\*\b(\S+)\b\*/<b>\1<\/b>/
 
 ``worker``
 ----------
 
 Parallel master/worker configuration. We currently perform working
 directory updates in parallel on Unix-like systems, which greatly
 helps performance.
 
 ``enabled``
     Whether to enable workers code to be used.
     (default: true)
 
 ``numcpus``
     Number of CPUs to use for parallel operations. A zero or
     negative value is treated as ``use the default``.
     (default: 4 or the number of CPUs on the system, whichever is larger)
 
 ``backgroundclose``
     Whether to enable closing file handles on background threads during certain
     operations. Some platforms aren't very efficient at closing file
     handles that have been written or appended to. By performing file closing
     on background threads, file write rate can increase substantially.
     (default: true on Windows, false elsewhere)
 
 ``backgroundcloseminfilecount``
     Minimum number of files required to trigger background file closing.
     Operations not writing this many files won't start background close
     threads.
     (default: 2048)
 
 ``backgroundclosemaxqueue``
     The maximum number of opened file handles waiting to be closed in the
     background. This option only has an effect if ``backgroundclose`` is
     enabled.
     (default: 384)
 
 ``backgroundclosethreadcount``
     Number of threads to process background file closes. Only relevant if
     ``backgroundclose`` is enabled.
     (default: 4)

rust/rhg/src/main.rs

@@ -1,818 +1,836 b''
 extern crate log;
 use crate::error::CommandError;
 use crate::ui::{local_to_utf8, Ui};
 use clap::App;
 use clap::AppSettings;
 use clap::Arg;
 use clap::ArgMatches;
 use format_bytes::{format_bytes, join};
 use hg::config::{Config, ConfigSource, PlainInfo};
 use hg::repo::{Repo, RepoError};
 use hg::utils::files::{get_bytes_from_os_str, get_path_from_bytes};
 use hg::utils::SliceExt;
 use hg::{exit_codes, requirements};
 use std::borrow::Cow;
 use std::collections::HashSet;
 use std::ffi::OsString;
 use std::os::unix::prelude::CommandExt;
 use std::path::PathBuf;
 use std::process::Command;
 
 mod blackbox;
 mod color;
 mod error;
 mod ui;
 pub mod utils {
     pub mod path_utils;
 }
 
 fn main_with_result(
     argv: Vec<OsString>,
     process_start_time: &blackbox::ProcessStartTime,
     ui: &ui::Ui,
     repo: Result<&Repo, &NoRepoInCwdError>,
     config: &Config,
 ) -> Result<(), CommandError> {
     check_unsupported(config, repo)?;
 
     let app = App::new("rhg")
         .global_setting(AppSettings::AllowInvalidUtf8)
         .global_setting(AppSettings::DisableVersion)
         .setting(AppSettings::SubcommandRequired)
         .setting(AppSettings::VersionlessSubcommands)
         .arg(
             Arg::with_name("repository")
                 .help("repository root directory")
                 .short("-R")
                 .long("--repository")
                 .value_name("REPO")
                 .takes_value(true)
                 // Both ok: `hg -R ./foo log` or `hg log -R ./foo`
                 .global(true),
         )
         .arg(
             Arg::with_name("config")
                 .help("set/override config option (use 'section.name=value')")
                 .long("--config")
                 .value_name("CONFIG")
                 .takes_value(true)
                 .global(true)
                 // Ok: `--config section.key1=val --config section.key2=val2`
                 .multiple(true)
                 // Not ok: `--config section.key1=val section.key2=val2`
                 .number_of_values(1),
         )
         .arg(
             Arg::with_name("cwd")
                 .help("change working directory")
                 .long("--cwd")
                 .value_name("DIR")
                 .takes_value(true)
                 .global(true),
         )
         .arg(
             Arg::with_name("color")
                 .help("when to colorize (boolean, always, auto, never, or debug)")
                 .long("--color")
                 .value_name("TYPE")
                 .takes_value(true)
                 .global(true),
         )
         .version("0.0.1");
     let app = add_subcommand_args(app);
 
     let matches = app.clone().get_matches_from_safe(argv.iter())?;
 
     let (subcommand_name, subcommand_matches) = matches.subcommand();
 
     // Mercurial allows users to define "defaults" for commands, fallback
     // if a default is detected for the current command
     let defaults = config.get_str(b"defaults", subcommand_name.as_bytes());
     if defaults?.is_some() {
         let msg = "`defaults` config set";
         return Err(CommandError::unsupported(msg));
     }
 
     for prefix in ["pre", "post", "fail"].iter() {
         // Mercurial allows users to define generic hooks for commands,
         // fallback if any are detected
         let item = format!("{}-{}", prefix, subcommand_name);
         let hook_for_command = config.get_str(b"hooks", item.as_bytes())?;
         if hook_for_command.is_some() {
             let msg = format!("{}-{} hook defined", prefix, subcommand_name);
             return Err(CommandError::unsupported(msg));
         }
     }
     let run = subcommand_run_fn(subcommand_name)
         .expect("unknown subcommand name from clap despite AppSettings::SubcommandRequired");
     let subcommand_args = subcommand_matches
         .expect("no subcommand arguments from clap despite AppSettings::SubcommandRequired");
 
     let invocation = CliInvocation {
         ui,
         subcommand_args,
         config,
         repo,
     };
 
     if let Ok(repo) = repo {
         // We don't support subrepos, fallback if the subrepos file is present
         if repo.working_directory_vfs().join(".hgsub").exists() {
             let msg = "subrepos (.hgsub is present)";
             return Err(CommandError::unsupported(msg));
         }
     }
 
     if config.is_extension_enabled(b"blackbox") {
         let blackbox =
             blackbox::Blackbox::new(&invocation, process_start_time)?;
         blackbox.log_command_start(argv.iter());
         let result = run(&invocation);
         blackbox.log_command_end(
             argv.iter(),
             exit_code(
                 &result,
                 // TODO: show a warning or combine with original error if
                 // `get_bool` returns an error
                 config
                     .get_bool(b"ui", b"detailed-exit-code")
                     .unwrap_or(false),
             ),
         );
         result
     } else {
         run(&invocation)
     }
 }
 
 fn rhg_main(argv: Vec<OsString>) -> ! {
     // Run this first, before we find out if the blackbox extension is even
     // enabled, in order to include everything in-between in the duration
     // measurements. Reading config files can be slow if they’re on NFS.
     let process_start_time = blackbox::ProcessStartTime::now();
 
     env_logger::init();
 
     let early_args = EarlyArgs::parse(&argv);
 
     let initial_current_dir = early_args.cwd.map(|cwd| {
         let cwd = get_path_from_bytes(&cwd);
         std::env::current_dir()
             .and_then(|initial| {
                 std::env::set_current_dir(cwd)?;
                 Ok(initial)
             })
             .unwrap_or_else(|error| {
                 exit(
                     &argv,
                     &None,
                     &Ui::new_infallible(&Config::empty()),
                     OnUnsupported::Abort,
                     Err(CommandError::abort(format!(
                         "abort: {}: '{}'",
                         error,
                         cwd.display()
                     ))),
                     false,
                 )
             })
     });
 
     let mut non_repo_config =
         Config::load_non_repo().unwrap_or_else(|error| {
             // Normally this is decided based on config, but we don’t have that
             // available. As of this writing config loading never returns an
             // "unsupported" error but that is not enforced by the type system.
             let on_unsupported = OnUnsupported::Abort;
 
             exit(
                 &argv,
                 &initial_current_dir,
                 &Ui::new_infallible(&Config::empty()),
                 on_unsupported,
                 Err(error.into()),
                 false,
             )
         });
 
     non_repo_config
         .load_cli_args(early_args.config, early_args.color)
         .unwrap_or_else(|error| {
             exit(
                 &argv,
                 &initial_current_dir,
                 &Ui::new_infallible(&non_repo_config),
                 OnUnsupported::from_config(&non_repo_config),
                 Err(error.into()),
                 non_repo_config
                     .get_bool(b"ui", b"detailed-exit-code")
                     .unwrap_or(false),
             )
         });
 
     if let Some(repo_path_bytes) = &early_args.repo {
         lazy_static::lazy_static! {
             static ref SCHEME_RE: regex::bytes::Regex =
                 // Same as `_matchscheme` in `mercurial/util.py`
                 regex::bytes::Regex::new("^[a-zA-Z0-9+.\\-]+:").unwrap();
         }
         if SCHEME_RE.is_match(&repo_path_bytes) {
             exit(
                 &argv,
                 &initial_current_dir,
                 &Ui::new_infallible(&non_repo_config),
                 OnUnsupported::from_config(&non_repo_config),
                 Err(CommandError::UnsupportedFeature {
                     message: format_bytes!(
                         b"URL-like --repository {}",
                         repo_path_bytes
                     ),
                 }),
                 // TODO: show a warning or combine with original error if
                 // `get_bool` returns an error
                 non_repo_config
                     .get_bool(b"ui", b"detailed-exit-code")
                     .unwrap_or(false),
             )
         }
     }
     let repo_arg = early_args.repo.unwrap_or(Vec::new());
     let repo_path: Option<PathBuf> = {
         if repo_arg.is_empty() {
             None
         } else {
             let local_config = {
                 if std::env::var_os("HGRCSKIPREPO").is_none() {
                     // TODO: handle errors from find_repo_root
                     if let Ok(current_dir_path) = Repo::find_repo_root() {
                         let config_files = vec![
                             ConfigSource::AbsPath(
                                 current_dir_path.join(".hg/hgrc"),
                             ),
                             ConfigSource::AbsPath(
                                 current_dir_path.join(".hg/hgrc-not-shared"),
                             ),
                         ];
                         // TODO: handle errors from
                         // `load_from_explicit_sources`
                         Config::load_from_explicit_sources(config_files).ok()
                     } else {
                         None
                     }
                 } else {
                     None
                 }
             };
 
             let non_repo_config_val = {
                 let non_repo_val = non_repo_config.get(b"paths", &repo_arg);
                 match &non_repo_val {
                     Some(val) if val.len() > 0 => home::home_dir()
                         .unwrap_or_else(|| PathBuf::from("~"))
                         .join(get_path_from_bytes(val))
                         .canonicalize()
                         // TODO: handle error and make it similar to python
                         // implementation maybe?
                         .ok(),
                     _ => None,
                 }
             };
 
             let config_val = match &local_config {
                 None => non_repo_config_val,
                 Some(val) => {
                     let local_config_val = val.get(b"paths", &repo_arg);
                     match &local_config_val {
                         Some(val) if val.len() > 0 => {
                             // presence of a local_config assures that
                             // current_dir
                             // wont result in an Error
                             let canpath = hg::utils::current_dir()
                                 .unwrap()
                                 .join(get_path_from_bytes(val))
                                 .canonicalize();
                             canpath.ok().or(non_repo_config_val)
                         }
                         _ => non_repo_config_val,
                     }
                 }
             };
             config_val.or(Some(get_path_from_bytes(&repo_arg).to_path_buf()))
         }
     };
 
     let simple_exit =
         |ui: &Ui, config: &Config, result: Result<(), CommandError>| -> ! {
             exit(
                 &argv,
                 &initial_current_dir,
                 ui,
                 OnUnsupported::from_config(config),
                 result,
                 // TODO: show a warning or combine with original error if
                 // `get_bool` returns an error
                 non_repo_config
                     .get_bool(b"ui", b"detailed-exit-code")
                     .unwrap_or(false),
             )
         };
     let early_exit = |config: &Config, error: CommandError| -> ! {
         simple_exit(&Ui::new_infallible(config), &config, Err(error))
     };
     let repo_result = match Repo::find(&non_repo_config, repo_path.to_owned())
     {
         Ok(repo) => Ok(repo),
         Err(RepoError::NotFound { at }) if repo_path.is_none() => {
             // Not finding a repo is not fatal yet, if `-R` was not given
             Err(NoRepoInCwdError { cwd: at })
         }
         Err(error) => early_exit(&non_repo_config, error.into()),
     };
 
     let config = if let Ok(repo) = &repo_result {
         repo.config()
     } else {
         &non_repo_config
     };
 
     let mut config_cow = Cow::Borrowed(config);
     config_cow.to_mut().apply_plain(PlainInfo::from_env());
     if !ui::plain(Some("tweakdefaults"))
         && config_cow
             .as_ref()
             .get_bool(b"ui", b"tweakdefaults")
             .unwrap_or_else(|error| early_exit(&config, error.into()))
     {
         config_cow.to_mut().tweakdefaults()
     };
     let config = config_cow.as_ref();
     let ui = Ui::new(&config)
         .unwrap_or_else(|error| early_exit(&config, error.into()));
+
+    if let Ok(true) = config.get_bool(b"rhg", b"fallback-immediately") {
+        exit(
+            &argv,
+            &initial_current_dir,
+            &ui,
+            OnUnsupported::Fallback {
+                executable: config
+                    .get(b"rhg", b"fallback-executable")
+                    .map(ToOwned::to_owned),
+            },
+            Err(CommandError::unsupported(
+                "`rhg.fallback-immediately is true`",
+            )),
+            false,
+        )
+    }
+
     let result = main_with_result(
         argv.iter().map(|s| s.to_owned()).collect(),
         &process_start_time,
         &ui,
         repo_result.as_ref(),
         config,
     );
     simple_exit(&ui, &config, result)
 }
 
 fn main() -> ! {
     rhg_main(std::env::args_os().collect())
 }
 
 fn exit_code(
     result: &Result<(), CommandError>,
     use_detailed_exit_code: bool,
 ) -> i32 {
     match result {
         Ok(()) => exit_codes::OK,
         Err(CommandError::Abort {
             detailed_exit_code, ..
         }) => {
             if use_detailed_exit_code {
                 *detailed_exit_code
             } else {
                 exit_codes::ABORT
             }
         }
         Err(CommandError::Unsuccessful) => exit_codes::UNSUCCESSFUL,
         // Exit with a specific code and no error message to let a potential
         // wrapper script fallback to Python-based Mercurial.
         Err(CommandError::UnsupportedFeature { .. }) => {
             exit_codes::UNIMPLEMENTED
         }
         Err(CommandError::InvalidFallback { .. }) => {
             exit_codes::INVALID_FALLBACK
         }
     }
 }
 
 fn exit<'a>(
     original_args: &'a [OsString],
     initial_current_dir: &Option<PathBuf>,
     ui: &Ui,
     mut on_unsupported: OnUnsupported,
     result: Result<(), CommandError>,
     use_detailed_exit_code: bool,
 ) -> ! {
     if let (
         OnUnsupported::Fallback { executable },
         Err(CommandError::UnsupportedFeature { message }),
     ) = (&on_unsupported, &result)
     {
         let mut args = original_args.iter();
         let executable = match executable {
             None => {
                 exit_no_fallback(
                     ui,
                     OnUnsupported::Abort,
                     Err(CommandError::abort(
                         "abort: 'rhg.on-unsupported=fallback' without \
                                 'rhg.fallback-executable' set.",
                     )),
                     false,
                 );
             }
             Some(executable) => executable,
         };
         let executable_path = get_path_from_bytes(&executable);
         let this_executable = args.next().expect("exepcted argv[0] to exist");
         if executable_path == &PathBuf::from(this_executable) {
             // Avoid spawning infinitely many processes until resource
             // exhaustion.
             let _ = ui.write_stderr(&format_bytes!(
                 b"Blocking recursive fallback. The 'rhg.fallback-executable = {}' config \
                 points to `rhg` itself.\n",
                 executable
             ));
             on_unsupported = OnUnsupported::Abort
         } else {
             log::debug!("falling back (see trace-level log)");
             log::trace!("{}", local_to_utf8(message));
             if let Err(err) = which::which(executable_path) {
                 exit_no_fallback(
                     ui,
                     OnUnsupported::Abort,
                     Err(CommandError::InvalidFallback {
                         path: executable.to_owned(),
                         err: err.to_string(),
                     }),
                     use_detailed_exit_code,
                 )
             }
             // `args` is now `argv[1..]` since we’ve already consumed
             // `argv[0]`
             let mut command = Command::new(executable_path);
             command.args(args);
             if let Some(initial) = initial_current_dir {
                 command.current_dir(initial);
             }
             // We don't use subprocess because proper signal handling is harder
             // and we don't want to keep `rhg` around after a fallback anyway.
             // For example, if `rhg` is run in the background and falls back to
             // `hg` which, in turn, waits for a signal, we'll get stuck if
             // we're doing plain subprocess.
             //
             // If `exec` returns, we can only assume our process is very broken
             // (see its documentation), so only try to forward the error code
             // when exiting.
             let err = command.exec();
             std::process::exit(
                 err.raw_os_error().unwrap_or(exit_codes::ABORT),
             );
         }
     }
     exit_no_fallback(ui, on_unsupported, result, use_detailed_exit_code)
 }
 
 fn exit_no_fallback(
     ui: &Ui,
     on_unsupported: OnUnsupported,
     result: Result<(), CommandError>,
     use_detailed_exit_code: bool,
 ) -> ! {
     match &result {
         Ok(_) => {}
         Err(CommandError::Unsuccessful) => {}
         Err(CommandError::Abort { message, hint, .. }) => {
             // Ignore errors when writing to stderr, we’re already exiting
             // with failure code so there’s not much more we can do.
             if !message.is_empty() {
                 let _ = ui.write_stderr(&format_bytes!(b"{}\n", message));
             }
             if let Some(hint) = hint {
                 let _ = ui.write_stderr(&format_bytes!(b"({})\n", hint));
             }
         }
         Err(CommandError::UnsupportedFeature { message }) => {
             match on_unsupported {
                 OnUnsupported::Abort => {
                     let _ = ui.write_stderr(&format_bytes!(
                         b"unsupported feature: {}\n",
                         message
                     ));
                 }
                 OnUnsupported::AbortSilent => {}
                 OnUnsupported::Fallback { .. } => unreachable!(),
             }
         }
         Err(CommandError::InvalidFallback { path, err }) => {
             let _ = ui.write_stderr(&format_bytes!(
                 b"abort: invalid fallback '{}': {}\n",
                 path,
                 err.as_bytes(),
             ));
         }
     }
     std::process::exit(exit_code(&result, use_detailed_exit_code))
 }
 
 macro_rules! subcommands {
     ($( $command: ident )+) => {
         mod commands {
             $(
                 pub mod $command;
             )+
         }
 
         fn add_subcommand_args<'a, 'b>(app: App<'a, 'b>) -> App<'a, 'b> {
             app
             $(
                 .subcommand(commands::$command::args())
             )+
         }
 
         pub type RunFn = fn(&CliInvocation) -> Result<(), CommandError>;
 
         fn subcommand_run_fn(name: &str) -> Option<RunFn> {
             match name {
                 $(
                     stringify!($command) => Some(commands::$command::run),
                 )+
                 _ => None,
             }
         }
     };
 }
 
 subcommands! {
     cat
     debugdata
     debugrequirements
     debugignorerhg
     debugrhgsparse
     files
     root
     config
     status
 }
 
 pub struct CliInvocation<'a> {
     ui: &'a Ui,
     subcommand_args: &'a ArgMatches<'a>,
     config: &'a Config,
     /// References inside `Result` is a bit peculiar but allow
     /// `invocation.repo?` to work out with `&CliInvocation` since this
     /// `Result` type is `Copy`.
     repo: Result<&'a Repo, &'a NoRepoInCwdError>,
 }
 
 struct NoRepoInCwdError {
     cwd: PathBuf,
 }
 
 /// CLI arguments to be parsed "early" in order to be able to read
 /// configuration before using Clap. Ideally we would also use Clap for this,
 /// see <https://github.com/clap-rs/clap/discussions/2366>.
 ///
 /// These arguments are still declared when we do use Clap later, so that Clap
 /// does not return an error for their presence.
 struct EarlyArgs {
     /// Values of all `--config` arguments. (Possibly none)
     config: Vec<Vec<u8>>,
     /// Value of all the `--color` argument, if any.
     color: Option<Vec<u8>>,
     /// Value of the `-R` or `--repository` argument, if any.
     repo: Option<Vec<u8>>,
     /// Value of the `--cwd` argument, if any.
     cwd: Option<Vec<u8>>,
 }
 
 impl EarlyArgs {
     fn parse<'a>(args: impl IntoIterator<Item = &'a OsString>) -> Self {
         let mut args = args.into_iter().map(get_bytes_from_os_str);
         let mut config = Vec::new();
         let mut color = None;
         let mut repo = None;
         let mut cwd = None;
         // Use `while let` instead of `for` so that we can also call
         // `args.next()` inside the loop.
         while let Some(arg) = args.next() {
             if arg == b"--config" {
                 if let Some(value) = args.next() {
                     config.push(value)
                 }
             } else if let Some(value) = arg.drop_prefix(b"--config=") {
                 config.push(value.to_owned())
             }
 
             if arg == b"--color" {
                 if let Some(value) = args.next() {
                     color = Some(value)
                 }
             } else if let Some(value) = arg.drop_prefix(b"--color=") {
                 color = Some(value.to_owned())
             }
 
             if arg == b"--cwd" {
                 if let Some(value) = args.next() {
                     cwd = Some(value)
                 }
             } else if let Some(value) = arg.drop_prefix(b"--cwd=") {
                 cwd = Some(value.to_owned())
             }
 
             if arg == b"--repository" || arg == b"-R" {
                 if let Some(value) = args.next() {
                     repo = Some(value)
                 }
             } else if let Some(value) = arg.drop_prefix(b"--repository=") {
                 repo = Some(value.to_owned())
             } else if let Some(value) = arg.drop_prefix(b"-R") {
                 repo = Some(value.to_owned())
             }
         }
         Self {
             config,
             color,
             repo,
             cwd,
         }
     }
 }
 
 /// What to do when encountering some unsupported feature.
 ///
 /// See `HgError::UnsupportedFeature` and `CommandError::UnsupportedFeature`.
 enum OnUnsupported {
     /// Print an error message describing what feature is not supported,
     /// and exit with code 252.
     Abort,
     /// Silently exit with code 252.
     AbortSilent,
     /// Try running a Python implementation
     Fallback { executable: Option<Vec<u8>> },
 }
 
 impl OnUnsupported {
     const DEFAULT: Self = OnUnsupported::Abort;
 
     fn from_config(config: &Config) -> Self {
         match config
             .get(b"rhg", b"on-unsupported")
             .map(|value| value.to_ascii_lowercase())
             .as_deref()
         {
             Some(b"abort") => OnUnsupported::Abort,
             Some(b"abort-silent") => OnUnsupported::AbortSilent,
             Some(b"fallback") => OnUnsupported::Fallback {
                 executable: config
                     .get(b"rhg", b"fallback-executable")
                     .map(|x| x.to_owned()),
             },
             None => Self::DEFAULT,
             Some(_) => {
                 // TODO: warn about unknown config value
                 Self::DEFAULT
             }
         }
     }
 }
 
 /// The `*` extension is an edge-case for config sub-options that apply to all
 /// extensions. For now, only `:required` exists, but that may change in the
 /// future.
 const SUPPORTED_EXTENSIONS: &[&[u8]] = &[
     b"blackbox",
     b"share",
     b"sparse",
     b"narrow",
     b"*",
     b"strip",
     b"rebase",
 ];
 
 fn check_extensions(config: &Config) -> Result<(), CommandError> {
     if let Some(b"*") = config.get(b"rhg", b"ignored-extensions") {
         // All extensions are to be ignored, nothing to do here
         return Ok(());
     }
 
     let enabled: HashSet<&[u8]> = config
         .iter_section(b"extensions")
         .filter_map(|(extension, value)| {
             if value == b"!" {
                 // Filter out disabled extensions
                 return None;
             }
             // Ignore extension suboptions. Only `required` exists for now.
             // `rhg` either supports an extension or doesn't, so it doesn't
             // make sense to consider the loading of an extension.
             let actual_extension =
                 extension.split_2(b':').unwrap_or((extension, b"")).0;
             Some(actual_extension)
         })
         .collect();
 
     let mut unsupported = enabled;
     for supported in SUPPORTED_EXTENSIONS {
         unsupported.remove(supported);
     }
 
     if let Some(ignored_list) = config.get_list(b"rhg", b"ignored-extensions")
     {
         for ignored in ignored_list {
             unsupported.remove(ignored.as_slice());
         }
     }
 
     if unsupported.is_empty() {
         Ok(())
     } else {
         let mut unsupported: Vec<_> = unsupported.into_iter().collect();
         // Sort the extensions to get a stable output
         unsupported.sort();
         Err(CommandError::UnsupportedFeature {
             message: format_bytes!(
                 b"extensions: {} (consider adding them to 'rhg.ignored-extensions' config)",
                 join(unsupported, b", ")
             ),
         })
     }
 }
 
 /// Array of tuples of (auto upgrade conf, feature conf, local requirement)
 const AUTO_UPGRADES: &[((&str, &str), (&str, &str), &str)] = &[
     (
         ("format", "use-share-safe.automatic-upgrade-of-mismatching-repositories"),
         ("format", "use-share-safe"),
         requirements::SHARESAFE_REQUIREMENT,
     ),
     (
         ("format", "use-dirstate-tracked-hint.automatic-upgrade-of-mismatching-repositories"),
         ("format", "use-dirstate-tracked-hint"),
         requirements::DIRSTATE_TRACKED_HINT_V1,
     ),
     (
         ("format", "use-dirstate-v2.automatic-upgrade-of-mismatching-repositories"),
         ("format", "use-dirstate-v2"),
         requirements::DIRSTATE_V2_REQUIREMENT,
     ),
 ];
 
 /// Mercurial allows users to automatically upgrade their repository.
 /// `rhg` does not have the ability to upgrade yet, so fallback if an upgrade
 /// is needed.
 fn check_auto_upgrade(
     config: &Config,
     reqs: &HashSet<String>,
 ) -> Result<(), CommandError> {
     for (upgrade_conf, feature_conf, local_req) in AUTO_UPGRADES.iter() {
         let auto_upgrade = config
             .get_bool(upgrade_conf.0.as_bytes(), upgrade_conf.1.as_bytes())?;
 
         if auto_upgrade {
             let want_it = config.get_bool(
                 feature_conf.0.as_bytes(),
                 feature_conf.1.as_bytes(),
             )?;
             let have_it = reqs.contains(*local_req);
 
             let action = match (want_it, have_it) {
                 (true, false) => Some("upgrade"),
                 (false, true) => Some("downgrade"),
                 _ => None,
             };
             if let Some(action) = action {
                 let message = format!(
                     "automatic {} {}.{}",
                     action, upgrade_conf.0, upgrade_conf.1
                 );
                 return Err(CommandError::unsupported(message));
             }
         }
     }
     Ok(())
 }
 
 fn check_unsupported(
     config: &Config,
     repo: Result<&Repo, &NoRepoInCwdError>,
 ) -> Result<(), CommandError> {
     check_extensions(config)?;
 
     if std::env::var_os("HG_PENDING").is_some() {
         // TODO: only if the value is `== repo.working_directory`?
         // What about relative v.s. absolute paths?
         Err(CommandError::unsupported("$HG_PENDING"))?
     }
 
     if let Ok(repo) = repo {
         if repo.has_subrepos()? {
             Err(CommandError::unsupported("sub-repositories"))?
         }
         check_auto_upgrade(config, repo.requirements())?;
     }
 
     if config.has_non_empty_section(b"encode") {
         Err(CommandError::unsupported("[encode] config"))?
     }
 
     if config.has_non_empty_section(b"decode") {
         Err(CommandError::unsupported("[decode] config"))?
     }
 
     Ok(())
 }

tests/test-rhg.t

@@ -1,400 +1,404 b''
 #require rhg
 
   $ NO_FALLBACK="env RHG_ON_UNSUPPORTED=abort"
 
 Unimplemented command
   $ $NO_FALLBACK rhg unimplemented-command
   unsupported feature: error: Found argument 'unimplemented-command' which wasn't expected, or isn't valid in this context
   
   USAGE:
       rhg [OPTIONS] <SUBCOMMAND>
   
   For more information try --help
   
   [252]
   $ rhg unimplemented-command --config rhg.on-unsupported=abort-silent
   [252]
 
 Finding root
   $ $NO_FALLBACK rhg root
   abort: no repository found in '$TESTTMP' (.hg not found)!
   [255]
 
   $ hg init repository
   $ cd repository
   $ $NO_FALLBACK rhg root
   $TESTTMP/repository
 
 Reading and setting configuration
   $ echo "[ui]" >> $HGRCPATH
   $ echo "username = user1" >> $HGRCPATH
   $ $NO_FALLBACK rhg config ui.username
   user1
   $ echo "[ui]" >> .hg/hgrc
   $ echo "username = user2" >> .hg/hgrc
   $ $NO_FALLBACK rhg config ui.username
   user2
   $ $NO_FALLBACK rhg --config ui.username=user3 config ui.username
   user3
 
 Unwritable file descriptor
   $ $NO_FALLBACK rhg root > /dev/full
   abort: No space left on device (os error 28)
   [255]
 
 Deleted repository
   $ rm -rf `pwd`
   $ $NO_FALLBACK rhg root
   abort: error getting current working directory: $ENOENT$
   [255]
 
 Listing tracked files
   $ cd $TESTTMP
   $ hg init repository
   $ cd repository
   $ for i in 1 2 3; do
   >   echo $i >> file$i
   >   hg add file$i
   > done
   > hg commit -m "commit $i" -q
 
 Listing tracked files from root
   $ $NO_FALLBACK rhg files
   file1
   file2
   file3
 
 Listing tracked files from subdirectory
   $ mkdir -p path/to/directory
   $ cd path/to/directory
   $ $NO_FALLBACK rhg files
   ../../../file1
   ../../../file2
   ../../../file3
 
 Listing tracked files through broken pipe
   $ $NO_FALLBACK rhg files | head -n 1
   ../../../file1
 
 Debuging data in inline index
   $ cd $TESTTMP
   $ rm -rf repository
   $ hg init repository
   $ cd repository
   $ for i in 1 2 3 4 5 6; do
   >   echo $i >> file-$i
   >   hg add file-$i
   >   hg commit -m "Commit $i" -q
   > done
   $ $NO_FALLBACK rhg debugdata -c 2
   8d0267cb034247ebfa5ee58ce59e22e57a492297
   test
   0 0
   file-3
   
   Commit 3 (no-eol)
   $ $NO_FALLBACK rhg debugdata -m 2
   file-1\x00b8e02f6433738021a065f94175c7cd23db5f05be (esc)
   file-2\x005d9299349fc01ddd25d0070d149b124d8f10411e (esc)
   file-3\x002661d26c649684b482d10f91960cc3db683c38b4 (esc)
 
 Debuging with full node id
   $ $NO_FALLBACK rhg debugdata -c `hg log -r 0 -T '{node}'`
   d1d1c679d3053e8926061b6f45ca52009f011e3f
   test
   0 0
   file-1
   
   Commit 1 (no-eol)
 
 Specifying revisions by changeset ID
   $ hg log -T '{node}\n'
   c6ad58c44207b6ff8a4fbbca7045a5edaa7e908b
   d654274993d0149eecc3cc03214f598320211900
   f646af7e96481d3a5470b695cf30ad8e3ab6c575
   cf8b83f14ead62b374b6e91a0e9303b85dfd9ed7
   91c6f6e73e39318534dc415ea4e8a09c99cd74d6
   6ae9681c6d30389694d8701faf24b583cf3ccafe
   $ $NO_FALLBACK rhg files -r cf8b83
   file-1
   file-2
   file-3
   $ $NO_FALLBACK rhg cat -r cf8b83 file-2
   2
   $ $NO_FALLBACK rhg cat --rev cf8b83 file-2
   2
   $ $NO_FALLBACK rhg cat -r c file-2
   abort: ambiguous revision identifier: c
   [255]
   $ $NO_FALLBACK rhg cat -r d file-2
   2
   $ $NO_FALLBACK rhg cat -r 0000 file-2
   file-2: no such file in rev 000000000000
   [1]
 
 Cat files
   $ cd $TESTTMP
   $ rm -rf repository
   $ hg init repository
   $ cd repository
   $ echo "original content" > original
   $ hg add original
   $ hg commit -m "add original" original
 Without `--rev`
   $ $NO_FALLBACK rhg cat original
   original content
 With `--rev`
   $ $NO_FALLBACK rhg cat -r 0 original
   original content
 Cat copied file should not display copy metadata
   $ hg copy original copy_of_original
   $ hg commit -m "add copy of original"
   $ $NO_FALLBACK rhg cat original
   original content
   $ $NO_FALLBACK rhg cat -r 1 copy_of_original
   original content
 
 
 Fallback to Python
   $ $NO_FALLBACK rhg cat original --exclude="*.rs"
   unsupported feature: error: Found argument '--exclude' which wasn't expected, or isn't valid in this context
   
   USAGE:
       rhg cat [OPTIONS] <FILE>...
   
   For more information try --help
   
   [252]
   $ rhg cat original --exclude="*.rs"
   original content
 
+Check that `fallback-immediately` overrides `$NO_FALLBACK`
+  $ $NO_FALLBACK rhg cat original --exclude="*.rs" --config rhg.fallback-immediately=1
+  original content
+
   $ (unset RHG_FALLBACK_EXECUTABLE; rhg cat original --exclude="*.rs")
   abort: 'rhg.on-unsupported=fallback' without 'rhg.fallback-executable' set.
   [255]
 
   $ (unset RHG_FALLBACK_EXECUTABLE; rhg cat original)
   original content
 
   $ rhg cat original --exclude="*.rs" --config rhg.fallback-executable=false
   [1]
 
   $ rhg cat original --exclude="*.rs" --config rhg.fallback-executable=hg-non-existent
   abort: invalid fallback 'hg-non-existent': cannot find binary path
   [253]
 
   $ rhg cat original --exclude="*.rs" --config rhg.fallback-executable=rhg
   Blocking recursive fallback. The 'rhg.fallback-executable = rhg' config points to `rhg` itself.
   unsupported feature: error: Found argument '--exclude' which wasn't expected, or isn't valid in this context
   
   USAGE:
       rhg cat [OPTIONS] <FILE>...
   
   For more information try --help
   
   [252]
 
 Fallback with shell path segments
   $ $NO_FALLBACK rhg cat .
   unsupported feature: `..` or `.` path segment
   [252]
   $ $NO_FALLBACK rhg cat ..
   unsupported feature: `..` or `.` path segment
   [252]
   $ $NO_FALLBACK rhg cat ../..
   unsupported feature: `..` or `.` path segment
   [252]
 
 Fallback with filesets
   $ $NO_FALLBACK rhg cat "set:c or b"
   unsupported feature: fileset
   [252]
 
 Fallback with generic hooks
   $ $NO_FALLBACK rhg cat original --config hooks.pre-cat=something
   unsupported feature: pre-cat hook defined
   [252]
 
   $ $NO_FALLBACK rhg cat original --config hooks.post-cat=something
   unsupported feature: post-cat hook defined
   [252]
 
   $ $NO_FALLBACK rhg cat original --config hooks.fail-cat=something
   unsupported feature: fail-cat hook defined
   [252]
 
 Fallback with [defaults]
   $ $NO_FALLBACK rhg cat original --config "defaults.cat=-r null"
   unsupported feature: `defaults` config set
   [252]
 
 
 Requirements
   $ $NO_FALLBACK rhg debugrequirements
   dotencode
   fncache
   generaldelta
   persistent-nodemap
   revlog-compression-zstd (zstd !)
   revlogv1
   share-safe
   sparserevlog
   store
 
   $ echo indoor-pool >> .hg/requires
   $ $NO_FALLBACK rhg files
   unsupported feature: repository requires feature unknown to this Mercurial: indoor-pool
   [252]
 
   $ $NO_FALLBACK rhg cat -r 1 copy_of_original
   unsupported feature: repository requires feature unknown to this Mercurial: indoor-pool
   [252]
 
   $ $NO_FALLBACK rhg debugrequirements
   unsupported feature: repository requires feature unknown to this Mercurial: indoor-pool
   [252]
 
   $ echo -e '\xFF' >> .hg/requires
   $ $NO_FALLBACK rhg debugrequirements
   abort: parse error in 'requires' file
   [255]
 
 Persistent nodemap
   $ cd $TESTTMP
   $ rm -rf repository
   $ hg --config format.use-persistent-nodemap=no init repository
   $ cd repository
   $ $NO_FALLBACK rhg debugrequirements | grep nodemap
   [1]
   $ hg debugbuilddag .+5000 --overwritten-file --config "storage.revlog.nodemap.mode=warn"
   $ hg id -r tip
   c3ae8dec9fad tip
   $ ls .hg/store/00changelog*
   .hg/store/00changelog.d
   .hg/store/00changelog.i
   $ $NO_FALLBACK rhg files -r c3ae8dec9fad
   of
 
   $ cd $TESTTMP
   $ rm -rf repository
   $ hg --config format.use-persistent-nodemap=True init repository
   $ cd repository
   $ $NO_FALLBACK rhg debugrequirements | grep nodemap
   persistent-nodemap
   $ hg debugbuilddag .+5000 --overwritten-file --config "storage.revlog.nodemap.mode=warn"
   $ hg id -r tip
   c3ae8dec9fad tip
   $ ls .hg/store/00changelog*
   .hg/store/00changelog-*.nd (glob)
   .hg/store/00changelog.d
   .hg/store/00changelog.i
   .hg/store/00changelog.n
 
 Specifying revisions by changeset ID
   $ $NO_FALLBACK rhg files -r c3ae8dec9fad
   of
   $ $NO_FALLBACK rhg cat -r c3ae8dec9fad of
   r5000
 
 Crate a shared repository
 
   $ echo "[extensions]"      >> $HGRCPATH
   $ echo "share = "          >> $HGRCPATH
 
   $ cd $TESTTMP
   $ hg init repo1
   $ echo a > repo1/a
   $ hg -R repo1 commit -A -m'init'
   adding a
 
   $ hg share repo1 repo2
   updating working directory
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
 
 And check that basic rhg commands work with sharing
 
   $ $NO_FALLBACK rhg files -R repo2
   repo2/a
   $ $NO_FALLBACK rhg -R repo2 cat -r 0 repo2/a
   a
 
 Same with relative sharing
 
   $ hg share repo2 repo3 --relative
   updating working directory
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
 
   $ $NO_FALLBACK rhg files -R repo3
   repo3/a
   $ $NO_FALLBACK rhg -R repo3 cat -r 0 repo3/a
   a
 
 Same with share-safe
 
   $ echo "[format]"         >> $HGRCPATH
   $ echo "use-share-safe = True" >> $HGRCPATH
 
   $ cd $TESTTMP
   $ hg init repo4
   $ cd repo4
   $ echo a > a
   $ hg commit -A -m'init'
   adding a
 
   $ cd ..
   $ hg share repo4 repo5
   updating working directory
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
 
 And check that basic rhg commands work with sharing
 
   $ cd repo5
   $ $NO_FALLBACK rhg files
   a
   $ $NO_FALLBACK rhg cat -r 0 a
   a
 
 The blackbox extension is supported
 
   $ echo "[extensions]" >> $HGRCPATH
   $ echo "blackbox =" >> $HGRCPATH
   $ echo "[blackbox]" >> $HGRCPATH
   $ echo "maxsize = 1" >> $HGRCPATH
   $ $NO_FALLBACK rhg files > /dev/null
   $ cat .hg/blackbox.log
   ????-??-?? ??:??:??.??? * @d3873e73d99ef67873dac33fbcc66268d5d2b6f4 (*)> (rust) files exited 0 after * seconds (glob)
   $ cat .hg/blackbox.log.1
   ????-??-?? ??:??:??.??? * @d3873e73d99ef67873dac33fbcc66268d5d2b6f4 (*)> (rust) files (glob)
 
 Subrepos are not supported
 
   $ touch .hgsub
   $ $NO_FALLBACK rhg files
   unsupported feature: subrepos (.hgsub is present)
   [252]
   $ rhg files
   a
   $ rm .hgsub
 
 The `:required` extension suboptions are correctly ignored
 
   $ echo "[extensions]" >> $HGRCPATH
   $ echo "blackbox:required = yes" >> $HGRCPATH
   $ rhg files
   a
   $ echo "*:required = yes" >> $HGRCPATH
   $ rhg files
   a
 
 We can ignore all extensions at once
 
   $ echo "[extensions]" >> $HGRCPATH
   $ echo "thisextensionbetternotexist=" >> $HGRCPATH
   $ echo "thisextensionbetternotexisteither=" >> $HGRCPATH
   $ $NO_FALLBACK rhg files
   unsupported feature: extensions: thisextensionbetternotexist, thisextensionbetternotexisteither (consider adding them to 'rhg.ignored-extensions' config)
   [252]
 
   $ echo "[rhg]" >> $HGRCPATH
   $ echo "ignored-extensions=*" >> $HGRCPATH
   $ $NO_FALLBACK rhg files
   a