help: include bookmarks in 'help revisions' and simplify wording

mercurial/help/revisions.txt

@@ -1,29 +1,29 b''
 Mercurial supports several ways to specify individual revisions.
 
 A plain integer is treated as a revision number. Negative integers are
 treated as sequential offsets from the tip, with -1 denoting the tip,
 -2 denoting the revision prior to the tip, and so forth.
 
 A 40-digit hexadecimal string is treated as a unique revision
 identifier.
 
 A hexadecimal string less than 40 characters long is treated as a
 unique revision identifier and is referred to as a short-form
 identifier. A short-form identifier is only valid if it is the prefix
 of exactly one full-length identifier.
 
-Any other string is treated as a tag or branch name. A tag name is a
-symbolic name associated with a revision identifier. A branch name
-denotes the tipmost revision of that branch. Tag and branch names must
-not contain the ":" character.
+Any other string is treated as a bookmark, tag, or branch name. A
+bookmark is a movable pointer to a revision. A tag is a permanent name
+associated with a revision. A branch name denotes the tipmost revision
+of that branch. Bookmark, tag, and branch names must not contain the ":"
+character.
 
-The reserved name "tip" is a special tag that always identifies the
-most recent revision.
+The reserved name "tip" always identifies the most recent revision.
 
 The reserved name "null" indicates the null revision. This is the
 revision of an empty repository, and the parent of revision 0.
 
 The reserved name "." indicates the working directory parent. If no
 working directory is checked out, it is equivalent to null. If an
 uncommitted merge is in progress, "." is the revision of the first
 parent.

tests/test-help.t

@@ -1,784 +1,784 b''
 Short help:
 
   $ hg
   Mercurial Distributed SCM
   
   basic commands:
   
    add         add the specified files on the next commit
    annotate    show changeset information by line for each file
    clone       make a copy of an existing repository
    commit      commit the specified files or all outstanding changes
    diff        diff repository (or selected files)
    export      dump the header and diffs for one or more changesets
    forget      forget the specified files on the next commit
    init        create a new repository in the given directory
    log         show revision history of entire repository or files
    merge       merge working directory with another revision
    phase       set or show the current phase name
    pull        pull changes from the specified source
    push        push changes to the specified destination
    remove      remove the specified files on the next commit
    serve       start stand-alone webserver
    status      show changed files in the working directory
    summary     summarize working directory state
    update      update working directory (or switch revisions)
   
   use "hg help" for the full list of commands or "hg -v" for details
 
   $ hg -q
    add         add the specified files on the next commit
    annotate    show changeset information by line for each file
    clone       make a copy of an existing repository
    commit      commit the specified files or all outstanding changes
    diff        diff repository (or selected files)
    export      dump the header and diffs for one or more changesets
    forget      forget the specified files on the next commit
    init        create a new repository in the given directory
    log         show revision history of entire repository or files
    merge       merge working directory with another revision
    phase       set or show the current phase name
    pull        pull changes from the specified source
    push        push changes to the specified destination
    remove      remove the specified files on the next commit
    serve       start stand-alone webserver
    status      show changed files in the working directory
    summary     summarize working directory state
    update      update working directory (or switch revisions)
 
   $ hg help
   Mercurial Distributed SCM
   
   list of commands:
   
    add           add the specified files on the next commit
    addremove     add all new files, delete all missing files
    annotate      show changeset information by line for each file
    archive       create an unversioned archive of a repository revision
    backout       reverse effect of earlier changeset
    bisect        subdivision search of changesets
    bookmarks     track a line of development with movable markers
    branch        set or show the current branch name
    branches      list repository named branches
    bundle        create a changegroup file
    cat           output the current or given revision of files
    clone         make a copy of an existing repository
    commit        commit the specified files or all outstanding changes
    copy          mark files as copied for the next commit
    diff          diff repository (or selected files)
    export        dump the header and diffs for one or more changesets
    forget        forget the specified files on the next commit
    graft         copy changes from other branches onto the current branch
    grep          search for a pattern in specified files and revisions
    heads         show current repository heads or show branch heads
    help          show help for a given topic or a help overview
    identify      identify the working copy or specified revision
    import        import an ordered set of patches
    incoming      show new changesets found in source
    init          create a new repository in the given directory
    locate        locate files matching specific patterns
    log           show revision history of entire repository or files
    manifest      output the current or given revision of the project manifest
    merge         merge working directory with another revision
    outgoing      show changesets not found in the destination
    parents       show the parents of the working directory or revision
    paths         show aliases for remote repositories
    phase         set or show the current phase name
    pull          pull changes from the specified source
    push          push changes to the specified destination
    recover       roll back an interrupted transaction
    remove        remove the specified files on the next commit
    rename        rename files; equivalent of copy + remove
    resolve       redo merges or set/view the merge status of files
    revert        restore files to their checkout state
    rollback      roll back the last transaction (dangerous)
    root          print the root (top) of the current working directory
    serve         start stand-alone webserver
    showconfig    show combined config settings from all hgrc files
    status        show changed files in the working directory
    summary       summarize working directory state
    tag           add one or more tags for the current or given revision
    tags          list repository tags
    tip           show the tip revision
    unbundle      apply one or more changegroup files
    update        update working directory (or switch revisions)
    verify        verify the integrity of the repository
    version       output version and copyright information
   
   additional help topics:
   
    config        Configuration Files
    dates         Date Formats
    diffs         Diff Formats
    environment   Environment Variables
    extensions    Using Additional Features
    filesets      Specifying File Sets
    glossary      Glossary
    hgignore      Syntax for Mercurial Ignore Files
    hgweb         Configuring hgweb
    merge-tools   Merge Tools
    multirevs     Specifying Multiple Revisions
    patterns      File Name Patterns
    phases        Working with Phases
    revisions     Specifying Single Revisions
    revsets       Specifying Revision Sets
    subrepos      Subrepositories
    templating    Template Usage
    urls          URL Paths
   
   use "hg -v help" to show builtin aliases and global options
 
   $ hg -q help
    add           add the specified files on the next commit
    addremove     add all new files, delete all missing files
    annotate      show changeset information by line for each file
    archive       create an unversioned archive of a repository revision
    backout       reverse effect of earlier changeset
    bisect        subdivision search of changesets
    bookmarks     track a line of development with movable markers
    branch        set or show the current branch name
    branches      list repository named branches
    bundle        create a changegroup file
    cat           output the current or given revision of files
    clone         make a copy of an existing repository
    commit        commit the specified files or all outstanding changes
    copy          mark files as copied for the next commit
    diff          diff repository (or selected files)
    export        dump the header and diffs for one or more changesets
    forget        forget the specified files on the next commit
    graft         copy changes from other branches onto the current branch
    grep          search for a pattern in specified files and revisions
    heads         show current repository heads or show branch heads
    help          show help for a given topic or a help overview
    identify      identify the working copy or specified revision
    import        import an ordered set of patches
    incoming      show new changesets found in source
    init          create a new repository in the given directory
    locate        locate files matching specific patterns
    log           show revision history of entire repository or files
    manifest      output the current or given revision of the project manifest
    merge         merge working directory with another revision
    outgoing      show changesets not found in the destination
    parents       show the parents of the working directory or revision
    paths         show aliases for remote repositories
    phase         set or show the current phase name
    pull          pull changes from the specified source
    push          push changes to the specified destination
    recover       roll back an interrupted transaction
    remove        remove the specified files on the next commit
    rename        rename files; equivalent of copy + remove
    resolve       redo merges or set/view the merge status of files
    revert        restore files to their checkout state
    rollback      roll back the last transaction (dangerous)
    root          print the root (top) of the current working directory
    serve         start stand-alone webserver
    showconfig    show combined config settings from all hgrc files
    status        show changed files in the working directory
    summary       summarize working directory state
    tag           add one or more tags for the current or given revision
    tags          list repository tags
    tip           show the tip revision
    unbundle      apply one or more changegroup files
    update        update working directory (or switch revisions)
    verify        verify the integrity of the repository
    version       output version and copyright information
   
   additional help topics:
   
    config        Configuration Files
    dates         Date Formats
    diffs         Diff Formats
    environment   Environment Variables
    extensions    Using Additional Features
    filesets      Specifying File Sets
    glossary      Glossary
    hgignore      Syntax for Mercurial Ignore Files
    hgweb         Configuring hgweb
    merge-tools   Merge Tools
    multirevs     Specifying Multiple Revisions
    patterns      File Name Patterns
    phases        Working with Phases
    revisions     Specifying Single Revisions
    revsets       Specifying Revision Sets
    subrepos      Subrepositories
    templating    Template Usage
    urls          URL Paths
 
 Test short command list with verbose option
 
   $ hg -v help shortlist
   Mercurial Distributed SCM
   
   basic commands:
   
    add:
         add the specified files on the next commit
    annotate, blame:
         show changeset information by line for each file
    clone:
         make a copy of an existing repository
    commit, ci:
         commit the specified files or all outstanding changes
    diff:
         diff repository (or selected files)
    export:
         dump the header and diffs for one or more changesets
    forget:
         forget the specified files on the next commit
    init:
         create a new repository in the given directory
    log, history:
         show revision history of entire repository or files
    merge:
         merge working directory with another revision
    phase:
         set or show the current phase name
    pull:
         pull changes from the specified source
    push:
         push changes to the specified destination
    remove, rm:
         remove the specified files on the next commit
    serve:
         start stand-alone webserver
    status, st:
         show changed files in the working directory
    summary, sum:
         summarize working directory state
    update, up, checkout, co:
         update working directory (or switch revisions)
   
   global options:
   
    -R --repository REPO   repository root directory or name of overlay bundle
                           file
       --cwd DIR           change working directory
    -y --noninteractive    do not prompt, automatically pick the first choice for
                           all prompts
    -q --quiet             suppress output
    -v --verbose           enable additional output
       --config CONFIG [+] set/override config option (use 'section.name=value')
       --debug             enable debugging output
       --debugger          start debugger
       --encoding ENCODE   set the charset encoding (default: ascii)
       --encodingmode MODE set the charset encoding mode (default: strict)
       --traceback         always print a traceback on exception
       --time              time how long the command takes
       --profile           print command execution profile
       --version           output version information and exit
    -h --help              display help and exit
   
   [+] marked option can be specified multiple times
   
   use "hg help" for the full list of commands
 
   $ hg add -h
   hg add [OPTION]... [FILE]...
   
   add the specified files on the next commit
   
       Schedule files to be version controlled and added to the repository.
   
       The files will be added to the repository at the next commit. To undo an
       add before that, see "hg forget".
   
       If no names are given, add all files to the repository.
   
       Returns 0 if all files are successfully added.
   
   options:
   
    -I --include PATTERN [+] include names matching the given patterns
    -X --exclude PATTERN [+] exclude names matching the given patterns
    -S --subrepos            recurse into subrepositories
    -n --dry-run             do not perform actions, just print output
   
   [+] marked option can be specified multiple times
   
   use "hg -v help add" to show more info
 
 Verbose help for add
 
   $ hg add -hv
   hg add [OPTION]... [FILE]...
   
   add the specified files on the next commit
   
       Schedule files to be version controlled and added to the repository.
   
       The files will be added to the repository at the next commit. To undo an
       add before that, see "hg forget".
   
       If no names are given, add all files to the repository.
   
       An example showing how new (unknown) files are added automatically by "hg
       add":
   
         $ ls
         foo.c
         $ hg status
         ? foo.c
         $ hg add
         adding foo.c
         $ hg status
         A foo.c
   
       Returns 0 if all files are successfully added.
   
   options:
   
    -I --include PATTERN [+] include names matching the given patterns
    -X --exclude PATTERN [+] exclude names matching the given patterns
    -S --subrepos            recurse into subrepositories
    -n --dry-run             do not perform actions, just print output
   
   [+] marked option can be specified multiple times
   
   global options:
   
    -R --repository REPO   repository root directory or name of overlay bundle
                           file
       --cwd DIR           change working directory
    -y --noninteractive    do not prompt, automatically pick the first choice for
                           all prompts
    -q --quiet             suppress output
    -v --verbose           enable additional output
       --config CONFIG [+] set/override config option (use 'section.name=value')
       --debug             enable debugging output
       --debugger          start debugger
       --encoding ENCODE   set the charset encoding (default: ascii)
       --encodingmode MODE set the charset encoding mode (default: strict)
       --traceback         always print a traceback on exception
       --time              time how long the command takes
       --profile           print command execution profile
       --version           output version information and exit
    -h --help              display help and exit
   
   [+] marked option can be specified multiple times
 
 Test help option with version option
 
   $ hg add -h --version
   Mercurial Distributed SCM (version *) (glob)
   (see http://mercurial.selenic.com for more information)
   
   Copyright (C) 2005-2012 Matt Mackall and others
   This is free software; see the source for copying conditions. There is NO
   warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 
   $ hg add --skjdfks
   hg add: option --skjdfks not recognized
   hg add [OPTION]... [FILE]...
   
   add the specified files on the next commit
   
   options:
   
    -I --include PATTERN [+] include names matching the given patterns
    -X --exclude PATTERN [+] exclude names matching the given patterns
    -S --subrepos            recurse into subrepositories
    -n --dry-run             do not perform actions, just print output
   
   [+] marked option can be specified multiple times
   
   use "hg help add" to show the full help text
   [255]
 
 Test ambiguous command help
 
   $ hg help ad
   list of commands:
   
    add          add the specified files on the next commit
    addremove    add all new files, delete all missing files
   
   use "hg -v help ad" to show builtin aliases and global options
 
 Test command without options
 
   $ hg help verify
   hg verify
   
   verify the integrity of the repository
   
       Verify the integrity of the current repository.
   
       This will perform an extensive check of the repository's integrity,
       validating the hashes and checksums of each entry in the changelog,
       manifest, and tracked files, as well as the integrity of their crosslinks
       and indices.
   
       Returns 0 on success, 1 if errors are encountered.
   
   use "hg -v help verify" to show more info
 
   $ hg help diff
   hg diff [OPTION]... ([-c REV] | [-r REV1 [-r REV2]]) [FILE]...
   
   diff repository (or selected files)
   
       Show differences between revisions for the specified files.
   
       Differences between files are shown using the unified diff format.
   
       Note:
          diff may generate unexpected results for merges, as it will default to
          comparing against the working directory's first parent changeset if no
          revisions are specified.
   
       When two revision arguments are given, then changes are shown between
       those revisions. If only one revision is specified then that revision is
       compared to the working directory, and, when no revisions are specified,
       the working directory files are compared to its parent.
   
       Alternatively you can specify -c/--change with a revision to see the
       changes in that changeset relative to its first parent.
   
       Without the -a/--text option, diff will avoid generating diffs of files it
       detects as binary. With -a, diff will generate a diff anyway, probably
       with undesirable results.
   
       Use the -g/--git option to generate diffs in the git extended diff format.
       For more information, read "hg help diffs".
   
       Returns 0 on success.
   
   options:
   
    -r --rev REV [+]         revision
    -c --change REV          change made by revision
    -a --text                treat all files as text
    -g --git                 use git extended diff format
       --nodates             omit dates from diff headers
    -p --show-function       show which function each change is in
       --reverse             produce a diff that undoes the changes
    -w --ignore-all-space    ignore white space when comparing lines
    -b --ignore-space-change ignore changes in the amount of white space
    -B --ignore-blank-lines  ignore changes whose lines are all blank
    -U --unified NUM         number of lines of context to show
       --stat                output diffstat-style summary of changes
    -I --include PATTERN [+] include names matching the given patterns
    -X --exclude PATTERN [+] exclude names matching the given patterns
    -S --subrepos            recurse into subrepositories
   
   [+] marked option can be specified multiple times
   
   use "hg -v help diff" to show more info
 
   $ hg help status
   hg status [OPTION]... [FILE]...
   
   aliases: st
   
   show changed files in the working directory
   
       Show status of files in the repository. If names are given, only files
       that match are shown. Files that are clean or ignored or the source of a
       copy/move operation, are not listed unless -c/--clean, -i/--ignored,
       -C/--copies or -A/--all are given. Unless options described with "show
       only ..." are given, the options -mardu are used.
   
       Option -q/--quiet hides untracked (unknown and ignored) files unless
       explicitly requested with -u/--unknown or -i/--ignored.
   
       Note:
          status may appear to disagree with diff if permissions have changed or
          a merge has occurred. The standard diff format does not report
          permission changes and diff only reports changes relative to one merge
          parent.
   
       If one revision is given, it is used as the base revision. If two
       revisions are given, the differences between them are shown. The --change
       option can also be used as a shortcut to list the changed files of a
       revision from its first parent.
   
       The codes used to show the status of files are:
   
         M = modified
         A = added
         R = removed
         C = clean
         ! = missing (deleted by non-hg command, but still tracked)
         ? = not tracked
         I = ignored
           = origin of the previous file listed as A (added)
   
       Returns 0 on success.
   
   options:
   
    -A --all                 show status of all files
    -m --modified            show only modified files
    -a --added               show only added files
    -r --removed             show only removed files
    -d --deleted             show only deleted (but tracked) files
    -c --clean               show only files without changes
    -u --unknown             show only unknown (not tracked) files
    -i --ignored             show only ignored files
    -n --no-status           hide status prefix
    -C --copies              show source of copied files
    -0 --print0              end filenames with NUL, for use with xargs
       --rev REV [+]         show difference from revision
       --change REV          list the changed files of a revision
    -I --include PATTERN [+] include names matching the given patterns
    -X --exclude PATTERN [+] exclude names matching the given patterns
    -S --subrepos            recurse into subrepositories
   
   [+] marked option can be specified multiple times
   
   use "hg -v help status" to show more info
 
   $ hg -q help status
   hg status [OPTION]... [FILE]...
   
   show changed files in the working directory
 
   $ hg help foo
   hg: unknown command 'foo'
   Mercurial Distributed SCM
   
   basic commands:
   
    add         add the specified files on the next commit
    annotate    show changeset information by line for each file
    clone       make a copy of an existing repository
    commit      commit the specified files or all outstanding changes
    diff        diff repository (or selected files)
    export      dump the header and diffs for one or more changesets
    forget      forget the specified files on the next commit
    init        create a new repository in the given directory
    log         show revision history of entire repository or files
    merge       merge working directory with another revision
    phase       set or show the current phase name
    pull        pull changes from the specified source
    push        push changes to the specified destination
    remove      remove the specified files on the next commit
    serve       start stand-alone webserver
    status      show changed files in the working directory
    summary     summarize working directory state
    update      update working directory (or switch revisions)
   
   use "hg help" for the full list of commands or "hg -v" for details
   [255]
 
   $ hg skjdfks
   hg: unknown command 'skjdfks'
   Mercurial Distributed SCM
   
   basic commands:
   
    add         add the specified files on the next commit
    annotate    show changeset information by line for each file
    clone       make a copy of an existing repository
    commit      commit the specified files or all outstanding changes
    diff        diff repository (or selected files)
    export      dump the header and diffs for one or more changesets
    forget      forget the specified files on the next commit
    init        create a new repository in the given directory
    log         show revision history of entire repository or files
    merge       merge working directory with another revision
    phase       set or show the current phase name
    pull        pull changes from the specified source
    push        push changes to the specified destination
    remove      remove the specified files on the next commit
    serve       start stand-alone webserver
    status      show changed files in the working directory
    summary     summarize working directory state
    update      update working directory (or switch revisions)
   
   use "hg help" for the full list of commands or "hg -v" for details
   [255]
 
   $ cat > helpext.py <<EOF
   > import os
   > from mercurial import commands
   > 
   > def nohelp(ui, *args, **kwargs):
   >     pass
   > 
   > cmdtable = {
   >     "nohelp": (nohelp, [], "hg nohelp"),
   > }
   > 
   > commands.norepo += ' nohelp'
   > EOF
   $ echo '[extensions]' >> $HGRCPATH
   $ echo "helpext = `pwd`/helpext.py" >> $HGRCPATH
 
 Test command with no help text
 
   $ hg help nohelp
   hg nohelp
   
   (no help text available)
   
   use "hg -v help nohelp" to show more info
 
 Test that default list of commands omits extension commands
 
   $ hg help
   Mercurial Distributed SCM
   
   list of commands:
   
    add           add the specified files on the next commit
    addremove     add all new files, delete all missing files
    annotate      show changeset information by line for each file
    archive       create an unversioned archive of a repository revision
    backout       reverse effect of earlier changeset
    bisect        subdivision search of changesets
    bookmarks     track a line of development with movable markers
    branch        set or show the current branch name
    branches      list repository named branches
    bundle        create a changegroup file
    cat           output the current or given revision of files
    clone         make a copy of an existing repository
    commit        commit the specified files or all outstanding changes
    copy          mark files as copied for the next commit
    diff          diff repository (or selected files)
    export        dump the header and diffs for one or more changesets
    forget        forget the specified files on the next commit
    graft         copy changes from other branches onto the current branch
    grep          search for a pattern in specified files and revisions
    heads         show current repository heads or show branch heads
    help          show help for a given topic or a help overview
    identify      identify the working copy or specified revision
    import        import an ordered set of patches
    incoming      show new changesets found in source
    init          create a new repository in the given directory
    locate        locate files matching specific patterns
    log           show revision history of entire repository or files
    manifest      output the current or given revision of the project manifest
    merge         merge working directory with another revision
    outgoing      show changesets not found in the destination
    parents       show the parents of the working directory or revision
    paths         show aliases for remote repositories
    phase         set or show the current phase name
    pull          pull changes from the specified source
    push          push changes to the specified destination
    recover       roll back an interrupted transaction
    remove        remove the specified files on the next commit
    rename        rename files; equivalent of copy + remove
    resolve       redo merges or set/view the merge status of files
    revert        restore files to their checkout state
    rollback      roll back the last transaction (dangerous)
    root          print the root (top) of the current working directory
    serve         start stand-alone webserver
    showconfig    show combined config settings from all hgrc files
    status        show changed files in the working directory
    summary       summarize working directory state
    tag           add one or more tags for the current or given revision
    tags          list repository tags
    tip           show the tip revision
    unbundle      apply one or more changegroup files
    update        update working directory (or switch revisions)
    verify        verify the integrity of the repository
    version       output version and copyright information
   
   enabled extensions:
   
    helpext       (no help text available)
   
   additional help topics:
   
    config        Configuration Files
    dates         Date Formats
    diffs         Diff Formats
    environment   Environment Variables
    extensions    Using Additional Features
    filesets      Specifying File Sets
    glossary      Glossary
    hgignore      Syntax for Mercurial Ignore Files
    hgweb         Configuring hgweb
    merge-tools   Merge Tools
    multirevs     Specifying Multiple Revisions
    patterns      File Name Patterns
    phases        Working with Phases
    revisions     Specifying Single Revisions
    revsets       Specifying Revision Sets
    subrepos      Subrepositories
    templating    Template Usage
    urls          URL Paths
   
   use "hg -v help" to show builtin aliases and global options
 
 
 
 Test list of commands with command with no help text
 
   $ hg help helpext
   helpext extension - no help text available
   
   list of commands:
   
    nohelp    (no help text available)
   
   use "hg -v help helpext" to show builtin aliases and global options
 
 Test a help topic
 
   $ hg help revs
   Specifying Single Revisions
   
       Mercurial supports several ways to specify individual revisions.
   
       A plain integer is treated as a revision number. Negative integers are
       treated as sequential offsets from the tip, with -1 denoting the tip, -2
       denoting the revision prior to the tip, and so forth.
   
       A 40-digit hexadecimal string is treated as a unique revision identifier.
   
       A hexadecimal string less than 40 characters long is treated as a unique
       revision identifier and is referred to as a short-form identifier. A
       short-form identifier is only valid if it is the prefix of exactly one
       full-length identifier.
   
-      Any other string is treated as a tag or branch name. A tag name is a
-      symbolic name associated with a revision identifier. A branch name denotes
-      the tipmost revision of that branch. Tag and branch names must not contain
-      the ":" character.
+      Any other string is treated as a bookmark, tag, or branch name. A bookmark
+      is a movable pointer to a revision. A tag is a permanent name associated
+      with a revision. A branch name denotes the tipmost revision of that
+      branch. Bookmark, tag, and branch names must not contain the ":"
+      character.
   
-      The reserved name "tip" is a special tag that always identifies the most
-      recent revision.
+      The reserved name "tip" always identifies the most recent revision.
   
       The reserved name "null" indicates the null revision. This is the revision
       of an empty repository, and the parent of revision 0.
   
       The reserved name "." indicates the working directory parent. If no
       working directory is checked out, it is equivalent to null. If an
       uncommitted merge is in progress, "." is the revision of the first parent.
 
 Test templating help
 
   $ hg help templating | egrep '(desc|diffstat|firstline|nonempty)  '
       desc          String. The text of the changeset description.
       diffstat      String. Statistics of changes with the following format:
       firstline     Any text. Returns the first line of text.
       nonempty      Any text. Returns '(none)' if the string is empty.
 
 Test help hooks
 
   $ cat > helphook1.py <<EOF
   > from mercurial import help
   > 
   > def rewrite(topic, doc):
   >     return doc + '\nhelphook1\n'
   > 
   > def extsetup(ui):
   >     help.addtopichook('revsets', rewrite)
   > EOF
   $ cat > helphook2.py <<EOF
   > from mercurial import help
   > 
   > def rewrite(topic, doc):
   >     return doc + '\nhelphook2\n'
   > 
   > def extsetup(ui):
   >     help.addtopichook('revsets', rewrite)
   > EOF
   $ echo '[extensions]' >> $HGRCPATH
   $ echo "helphook1 = `pwd`/helphook1.py" >> $HGRCPATH
   $ echo "helphook2 = `pwd`/helphook2.py" >> $HGRCPATH
   $ hg help revsets | grep helphook
       helphook1
       helphook2