relnotes/6.2

rust-index: using the `hg::index::Index` in ancestors iterator and lazy set

Since there is no Rust implementation for REVLOGV2/CHANGELOGv2, we declare
them to be incompatible with Rust, hence indexes in these formats will use
the implementations from Python `mercurial.ancestor`. If this is an unacceptable
performance hit for current users of these formats, we can later on add Rust
implementations based on the C index for them or implement these formats for
the Rust indexes.

Among the challenges that we had to meet, we wanted to avoid taking the GIL each
time the inner (vcsgraph) iterator has to call the parents function. This would probably
still be acceptable in terms of performance with `AncestorsIterator`, but not with
`LazyAncestors` nor for the upcoming change in `MissingAncestors`.

Hence we enclose the reference to the index in a `PySharedRef`, leading to more
rigourous checking of mutations, which does pass now that there no logically immutable
methods of `hg::index::Index` that take a mutable reference as input.

= Mercurial 6.2.2 =

 * fsmonitor: restore functionality by moving to new dirstate APIs
 * dirstate-v2: fix data file transaction handling (issue6730)
 * rust: fix behavior when matching files with multiple includes 
 * rust: widen range of compatible crates to help with packaging
 * rust-status: ignored directories are now correctly only listed if opted into
 * automation: improve Windows packaging tooling
 * contrib: update Mercurial install in bootstrap environment
 * Remove flakiness in some tests
 * Improve portability of certain `tar` uses in tests

= Mercurial 6.2.1 =

 * Fix SSL support in Python 3.6
 * git: make sure to fsdecode bookmark names everywhere (issue6723)
 * git: add a missing reset_copy keyword argument to dirstate.set_tracked()
 * git: copy findmissingrevs() from revlog.py to gitlog.py (issue6472)
 * packaging: update keyring on Windows to avoid spurious stacktraces
 * packaging: bump dulwich to 0.20.45
 * Fix typos in documentation for debugdiscovery
 * Miscellaneous improvements of debugdiscovery 

= Mercurial 6.2rc0 =

'''This is the first release to support Python 3.6+ ''only'''''

== New Features ==
 * Introduce a way to auto-upgrade a repo for certain requirements (see `hg help config.format`)
 * filemerge: add support for partial conflict resolution by external tool
 * contrib: add a partial-merge tool for sorted lists (such as Python imports)
 * revlog: reorder p1 and p2 when p1 is null and p2 is not while respecting issue6528
 * rhg: add support for ignoring all extensions
 * completion: install completers to conventional locations
 * revert: ask user to confirm before tracking new file when interactive
 * Rust implementation now uses the new dirstate API
 * sslutil: be less strict about which ciphers are allowed when using --insecure
 * sslutil: support TLSV1_ALERT_PROTOCOL_VERSION reason code
 * absorb: make `--edit-lines` imply `--apply-changes`
 * diff: add help text to highlight the ability to do merge diffs
 * censor: make rhg fall back to python when encountering a censored node
 * clone: use better names for temp files
 * debuglock: make the command more useful in non-interactive mode
 * debugdeltachain: distinct between snapshot and other diffs
 * debugindex: rename to debugindex debug-revlog-index
 * Make debug-revlog-index give out more information
 * sparse: use the rust code even when sparse is present

== Bug Fixes ==
 * Python 3 bugfixes
 * Windows bugfixes
 * templates: make `firstline` filter not keep '\v', '\f' and similar
 * rhg: sort unsupported extensions in error message
 * Improve performance of all functions that extract the first line of a text
 * crecord: avoid duplicating lines when reverting noeol->eol change
 * Some config.path options are now discoverable via config
 * mail: don't complain about a multi-word email.method
 * bundlespec: do not overwrite bundlespec value with the config one
 * bundlespec: do not check for `-` in the params portion of the bundlespec
 * bundlespec: handle the presence of obsmarker part
 * sparse: start moving away from the global variable for detection of usage
 * rust-changelog: don't skip empty lines when iterating over changeset lines
 * narrow: support debugupgraderepo
 * bundle: quick fix to ludicrous performance penalty
 * followlines: don't put Unicode directly into the .js file (issue6559)
 * manifest: improve error message in case for tree manifest
 * revlog: use %d to format int instead of %lu (issue6565)
 * revlog: use appropriate format char for int ("i" instead of I")
 * worker: stop relying on garbage collection to release memoryview
 * worker: implement _blockingreader.readinto() (issue6444)
 * worker: avoid potential partial write of pickled data

== Backwards Compatibility Changes ==
 * '''Removed Python 2 support''': this includes a lot of cleanup in our codebase, automation, testing, etc.
 * debugindex: rename to debugindex debug-revlog-index

== Miscellaneous ==

 * Fix typos and add missing items from documentation
 * dirstate-tree: optimize HashMap lookups with raw_entry_mut
 * Rust dependencies have been upgraded
 * revlog: rank computation is done by Rust when available
 * Improve discovery test tooling
 * Audit the number of queries done in discovery
 * Improved .hgignore of the mercurial-devel repository itself
 * Improve test coverage of dirstate-v2
 * rust-requirements: allow loading repos with `bookmarksinstore` requirement
 * Various Rust refactorings to help with revlog management
 * Improve debugability of Rust structs
 * Improve unit testing of the Rust dirstatemap
 * Improve robustness of the Rust dirstatemap to corruption
 * Improve changelog-v2 upgrade system