relnotes/6.1

'''This is the last release to support Python 2. Mercurial is Python 3 only starting with 6.2'''

= Mercurial 6.1rc0 =

== New Features ==
  * Added a way of specifying required extensions that prevent Mercurial from starting if they are not found. See `hg help config.extensions`.
  * Merge conflict markers have been made clearer (see backwards compatibility below)
  * Improve detailed error codes
  * Added a hint about mangled whitespace on bad patch
  * Explain which order the commits are presented in `chistedit`
  * Introduce a `dirstate-tracked-hint` feature to help automation keep track of changes to tracked files. See `hg help config.use-dirstate-tracked-hint`.
  * Shared repositories can be upgraded if the upgrade is specific to the share. For now, this only applies to `dirstate-v2` and `dirstate-tracked-hint`.
  * When using the `narrow` extension, non-conflicting changes to files outside of the narrow specification can now be merged.
  * When cloning a repository using stream-clone, the client can now control the repository format variants to use as long as the stream content does not restrict that variant.

== Default Format Change ==

These changes affect newly created repositories (or new clones) done with Mercurial 6.1.

  * The `share-safe` format variant is now enabled by default. It makes configuration and requirements more consistent across repository and their shares. This introduces a behavior change as shares from a repository using the new format will also use their main repository's configuration. See `hg help config.format.use-share-safe` for details about the feature and the available options for auto-upgrading existing shares.


== New Experimental Features ==
  * The pure Rust version of Mercurial called `rhg` added support for most common invocations of `hg status`. See `hg help rust.rhg` for details on how to try it out.
  * `rhg` supports narrow clones and sparse checkouts.

== Bug Fixes ==

  * '''Obsolete revisions are skipped while computing heads. In conjunction with the `evolve` extension >= 10.5.0, this leads to massive exchange (push/pull) speedups in repositories with a lot of heads and/or obsolete revisions.'''
  * Stream-clones now properly advertise all requirements needed. This can result in the stream-clone feature being disabled for some clients using < 6.0.2. A small bugfix patch for these older client is available if necessary.
  * The `--no-check` and `--no-merge` flags now properly overwrite the behavior from `commands.update.check`
  * `rhg`'s fallback detection is more robust in general in the presence of more advanced configs
  * `rhg`'s `blackbox` now supports milliseconds by default and uses the same ISO 8601 format as the Python implementation
  * Fix `rhg` crash on non-generaldelta revlogs
  * The `lfs`, `largefiles` and `sparse` extensions now correctly take the appropriate lock before writing requirements 
  * The `notify` extension does not produce errors anymore if a revision is not found
  * Remove unnecessary and overly strict check for divergence in `hg fix`
  * Windows compatibility improvements
  * Miscellaneous Python 3 and typing improvements
  * Many other small or internal fixes

== Backwards Compatibility Changes ==

  * The use of `share-safe`, means shares (of new repositories) will also use their main repository's configuration see the `Default Format Change` section for details.
  * The fix to stream-clone requirements advertising means some requirements previously (wrongly) omitted are now sent. This can confuse client using a Mercurial version < 6.0.2. The client would consider these requirements unsupported even if it actually know them. If you encounter this, either upgrade your client or apply the necessary patch.
  * The labels passed to merge tools have changed slightly. Merge tools can get labels passed to them if you include `$labellocal`, `$labelbase`, and/or `$labelother` in the `merge-tool.<tool name>.args` configuration. These labels used to have some space-padding, and truncation to fit within 72 columns. Both the padding and the truncation has been removed.
  * Some of the text in labels passed to merge tools has changed. For example, in conflicts while running `hg histedit`, the labels used to be "local", "base", and "histedit". They are now "already edited", "parent of current change", and "current change", respectively.
  * The computation of namedbranch heads now ignores obsolete revisions. User of the Changeset Evolution feature may see a change in location and numbers of heads of each named branches (and topic).
  * The remotefilelog extension now requires an appropriate excludepattern for subrepositories.
  * `debugsparse`'s interface has been reworked to be more flexible. Since it's a debug command it is not actually a breaking change, but it is worth noting here.
  * Temporary files for merges are now all inside a `hgmerge` directory instead of at the root of `TMPDIR`. The corresponding experimental `mergetempdirprefix` config option has been removed.

== Internal API Changes ==

  * The dirstate API received minor modifications.

== Miscellaneous ==

  * Removed exchange-v2. It was a prototype that had never been in a working state and had been left untouched since 2017.