rust-dirstate-v2: show `unused_bytes` counter is not reset on total rewrite This was picked up by @aalekseyev when doing unrelated debugging. The Rust implementation was never resetting this counter, so a brand new file would carry over the old counter. As I write this, my counter is a supposed 7389089 unused bytes for a total of 170978 bytes in the data file. Feel free to post your own high score. Differential Revision: https://phab.mercurial-scm.org/D12593

test-dirstate: use new `--docket` flag to get the data uuid This is more robust. Differential Revision: https://phab.mercurial-scm.org/D12592

debugcommands: remove `debugdirstateignorepatternhash` This is replaced by the more complete `--docket` option to `debugstate`. Differential Revision: https://phab.mercurial-scm.org/D12591

dirstate-v2: add flag to `debugstate` to print docket information This is useful information that we don't easily have access to currently, unless you speak fluent xxd. This replaces `debugdirstateignorepatternshash`, which I'll remove in the next changeset. Differential Revision: https://phab.mercurial-scm.org/D12590

doc: use an absolute path in sys.path to work around a python DLL loading bug This bug[1] was causing the zstd entry under "Available Compression Engines" to be omitted from the documentation for some versions of python3. I could upgrade, but past upgrades have broken venvs and clobbered installed packages. It's a trivial workaround, so there's no sense in leaving this subtle issue. It was flushed out by changing the module policy here from 'allow' to 'c', and seeing this error: ImportError: DLL load failed while importing parsers: The parameter is incorrect. [1] https://github.com/python/cpython/issues/87271 Differential Revision: https://phab.mercurial-scm.org/D12599

rhg: fix dirstate-v2 data file removal system In D12581 I introduced logic to remove the previous dirstate-v2 data file after a new one is created (and its corresponding docket), but the logic was flawed. I fixed it and made it simpler to understand by gather all logic in a single expression. Differential Revision: https://phab.mercurial-scm.org/D12586

rhg: use `Command::exec` instead of `Command::status` `rhg` is supposed to be a transparent executable, using a subprocess defeats that purpose. See inline comments for more details. This also introduces the `which` crate to check if the fallback executable actually exists to help debugging (plain `execve` doesn't give much information). The error code 253 is used to signify that the fallback is not found, but may mean in the future that it is otherwise invalid if we start being more specific. Differential Revision: https://phab.mercurial-scm.org/D12578

commit: don't use hard-coded `.hg/last-message.txt` path in error message Whoever wrote D8463 just used a hard-coded path to `.hg/last-message.text` instead of using the relative path that was already available in the `msgfn` variable (and used just a few lines up in related message). Let's fix that. Differential Revision: https://phab.mercurial-scm.org/D12585

branching: merge stable into default This also added the small fix need in Rust tests for the new `DirstateMap::pack_v2` API change in stable.

rust-dirstate-v2: clean up previous data file after the docket is written This was overlooked before and caused many data files to keep living forever. We could potentially consider adding a random cleanup of them in case they slipped through one day. Differential Revision: https://phab.mercurial-scm.org/D12581