relnotes/6.8

hghave: update expected rustfmt version

We still use nightly, but have moved to a newer nightly after the last
CI image upgrade in 74f1bf147a6d and 3876d4c6c79e.

= 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