relnotes: add 6.4.3

backup: fix issue when the backup end up in a different directory Because of store encoding, we might end up with the backup in a different directory than the initial copy (for example if the backup path make it cross the 120 char limit). This can create crash, especially since 6.4 where backup are used during revlog split. Making sure the directory exists fixes these crash We added a test covering this case. Strictly speaking, this has always been broken, however the new code in 6.4 triggers it more easily.

vfsproxy: inherit the `createmode` attribute too It is an important part of the API when creating directory. We will need it in the next changeset.

revlog: test more complex file pattern for revlog split There have been a report of failure while splitting revlog. The file name involved was important. The pattern involved here are not problematic, but it help to setup the machinery to test multiple files, the actual fix and problematic file will arrive in a later changeset.

repo-upgrade: write new requirement before upgrading the dirstate This will prevent a small race condition where another hg process still believes the repo is dirstate-v1 during the upgrade process. This is good to have, but it is not a proper fix for the underlying problem. There is code that assumes a requirement means a usage, e.g. having the `generaldelta` requirement would imply *all* revlogs to use general delta, but it's not true, it simply means that the repository advertises to the client it needs to understand `generaldelta` in order to read the repo. In the case of the dirstate, having the requirement *technically* should always be the same as using dirstate-v2, since there is only one dirstate and requirements should be as minimal as possible. However, we should not assume this and make the code more robust in a future patch (series).

perf: introduce a `perf::stream-locked-section` command This command benchmark the initial part of a stream clone, where the repository is locked.

transaction: tr._names are actually bytes, use byte string to join them Looks like this is never checked in the tests? But trying e.g. `print(tr)` by hand before this change would give: TypeError: sequence item 0: expected str instance, bytes found Looks like tr._names are always bytes (although this isn't actually enforced, but maybe at some point it will at least be type checked e.g. by pytype).

nix: add nix-defined package and devel env (flake) This adds a Nix Flake which defines: - package recipies to build and run Mercurial (C, C+Rust variants), - a meta package to run the test suite in an isolated sandbox, - a development environment with some tools (notably Python and the Black formatter, pinned to match the CI). Python is pinned to the recommended version. The Rust toolchain is a fairly recent one provided by the Nixpkgs channel. It is not yet pinned to the same version as the "reference" Debian package, but this does not seem to cause any issue. Example usage of local commands are provided in the `flake.nix` file. Once merged, it should also be possible to pull and run directly from the source repository directly with something like: `nix run hg+https://foss.heptapod.net/mercurial/mercurial-devel?ref=TOPIC&dir=contrib/nix' -- version`

hgignore: ignore nix result symlink

tests: add test ignore list for nix Some tests cannot run properly in the nix sandbox. This adds a list of tests to ignore when running in that context.