documentation: add `zstd` compression to the internal `revlogs` documentation Differential Revision: https://phab.mercurial-scm.org/D8953

extdiff: move single file handling inside `not per-file` conditional If `--per-file` is passed, we will diffing files one by one, hence there is no need to make this optimization around single file in that case. This optimization is only required when `--per-file` is not passed and we will be opening directory-diff for a single file. Differential Revision: https://phab.mercurial-scm.org/D8971

extdiff: remove dir2root and pass full path as dir2 in _runperfilediff() The only use of `dir2root` was to join with `dir2` to generate the path for other side of diff. Like in previous patch, `dir1a` and `dir1b` are full paths and no longer base names, hence we pass `dir2` as full path too and making `dir2root` unrequired. Differential Revision: https://phab.mercurial-scm.org/D8970

extdiff: pass full paths of `dir1a` and `dir1b` to `_runperfilediff()` Earlier we were passing basename instead of the fullpath and then joining with the tmproot. This is wrong because the user can choose `rev1a` as wdir and in those cases, tmproot should not be joined with the path. I am working on refactoring extdiff logic so that we can have options like `diff --tool` and encountered this. Although this patch in itself makes no difference, however in future when a new caller of `_runperfilediff()` will be added, it will be useful to directly pass on the full paths instead. Differential Revision: https://phab.mercurial-scm.org/D8969

merge with stable

mercurial: force LF endings for *.py, *.{c,h} and *.t in .editorconfig PyCharm on Windows otherwise uses CRLF. Differential Revision: https://phab.mercurial-scm.org/D8947

hooklib: update documentation of changeset_obsoletedfor for changed hook type This updates usage example of changeset_obsoleted to reflect the move from pretxnclose to txnclose made in 04ef381000a8 (hooklib: fix detection of successors for changeset_obsoleted). Differential Revision: https://phab.mercurial-scm.org/D8929

worker: don't expose readinto() on _blockingreader since pickle is picky The `pickle` module expects the input to be buffered and a whole object to be available when `pickle.load()` is called, which is not necessarily true when we send data from workers back to the parent process (i.e., it seems like a bad assumption for the `pickle` module to make). We added a workaround for that in https://phab.mercurial-scm.org/D8076, which made `read()` continue until all the requested bytes have been read. As we found out at work after a lot of investigation (I've spent the last two days on this), the native version of `pickle.load()` has started calling `readinto()` on the input since Python 3.8. That started being called in https://github.com/python/cpython/commit/91f4380cedbae32b49adbea2518014a5624c6523 (and only by the C version of `pickle.load()`)). Before that, it was only `read()` and `readline()` that were called. The problem with that was that `readinto()` on our `_blockingreader` was simply delegating to the underlying, *unbuffered* object. The symptom we saw was that `hg fix` started failing sometimes on Python 3.8 on Mac. It failed very relyable in some cases. I still haven't figured out under what circumstances it fails and I've been unable to reproduce it in test cases (I've tried writing larger amounts of data, using different numbers of workers, and making the formatters sleep). I have, however, been able to reproduce it 3-4 times on Linux, but then it stopped reproducing on the following few hundred attempts. To fix the problem, we can simply remove the implementation of `readinto()`, since the unpickler will then fall back to calling `read()`. The fallback was added a bit later, in https://github.com/python/cpython/commit/b19f7ecfa3adc6ba1544225317b9473649815b38. However, that commit also added checking that what `read()` returns is a `bytes`, so we also need to convert the `bytearray` we use into that. I was able to add a test for that failure at least. Differential Revision: https://phab.mercurial-scm.org/D8928

commit: clear mergestate also with --amend (issue6304) The `hg commit --amend` uses the in-memory code, which naturally doesn't touch the merge state (well, it shouldn't anyway; I think I've fixed bugs in that area recently). We therefore need to clear the mergestate after calling `repo.commitctx()` since we expect that from `hg commit --amend`. Differential Revision: https://phab.mercurial-scm.org/D8932

tests: add test showing that merge state is not cleared by amend This is slightly modified version of the test case I provided in issue6304. Differential Revision: https://phab.mercurial-scm.org/D8931