relnotes/6.8

scmutils: read the requires file before writing to avoid unnecessary rewrite

This lets us get away without the repo lock in situations where we need
to write requirements, but we know we're not changing the store requirements.

= Mercurial 6.8.1 =

 * Python 3.12: fix an issue between `threading` and `demandimport`
 * rhg: expand user and environment variable in paths to ignore in config and
   includes
 * `win32mbcs` extension: fix an encoding issue

= Mercurial 6.8 =

As usual, a *lot* of patches don't make it to this list.

== New Features or performance improvements ==

 * Phases have been reworked to improve their general performance
    * revset: stop serializing node when using "%ln"
    * phases: convert remote phase root to node while reading them
    * phases: use revision number in new_heads
    * phases: use revision number in analyze_remote_phases
    * phases: stop using `repo.set` in `remotephasessummary`
    * phases: move RemotePhasesSummary to revision number
    * phases: use revision number in `_pushdiscoveryphase`
    * phases: introduce a performant efficient way to access revision in a set
    * phases: rework the logic of _pushdiscoveryphase to bound complexity
 * The Rust working copy code is being used by more places now:
     * matchers: support patternmatcher in rust
     * dirstate: remove the python-side whitelist of allowed matchers
 * stream-clone: disable gc for `_entries_walk` duration
 * stream-clone: disable gc for the initial section for the v3 format
 * postincoming: avoid computing branchhead if no report will be posted
 * stream-clone: disable gc for the entry listing section for the v2 format
 * perf: allow profiling of more than one run
 * perf: run the gc before each run
 * perf: start recording total time after warming
 * perf: clear vfs audit_cache before each run
 * outgoing: rework the handling of the `missingroots` case to be faster
 * outgoing: add a simple fastpath when there is no common
 * tags-cache: skip the filternode step if we are not going to use it
 * tags-cache: directly operate on rev-num warming hgtagsfnodescache
 * tags-cache: directly perform a monimal walk for hgtagsfnodescache warming

== New Experimental Features ==

 * Introduce a new experimental branch cache "v3":
    * branchcache: add more test for the logic around obsolescence and branch heads
    * branchcache: skip entries that are topological heads in the on disk file
    * branchcache: add a "pure topological head" fast path
    * branchcache: allow to detect "pure topological case" for branchmap

== Bug Fixes ==

 * rust: use `cpython` 0.7.2 crate to add support for Python 3.12
 * perf-stream-locked-section: actually use v1 generation when requested
 * perf-stream-locked-section: fix the call to the v3 generator
 * perf-stream-locked-section: advertise the right version key in the help
 * stream: in v3, skip the "size" fast path if the entries have some unknown size
 * stream-clone: stop getting the file size of all file in v3
 * streamclone: stop listing files for entries that have no volatile files
 * perf-stream-consume: use the source repository config when applying
 * bundle: do no check the changegroup version if no changegroup is included
 * perf: create the temporary target next to the source in stream-consume
 * bundlespec: fix the "streamv2" and "streamv3-exp" variant
 * push: rework the computation of fallbackheads to be correct
 * profiler: flush after writing the profiler output
 * base-revsets: use an author that actually exercises a lot of changesets
 * hgrc: search XDG_CONFIG_HOME on mac
 * clonebundles: add missing newline to legacy response
 * narrow: add a test for linkrev computation done during widen
 * Multiple fixes to guard against mmap issues
 * portability: fix build on Solaris-derived systemd

== Backwards Compatibility Changes ==

== Internal API Changes ==

== Miscellaneous ==

 * obsolete: quote the feature name