merge with stable

makefile: run Rust tests if cargo is installed While no particular minimum toolchain version is targeted as of yet, this serves as a first step to make more people/machines run the Rust tests.

merge: hint about using `hg resolve` for resolving conflicts This was suggested by one of our users at Google. Makes sense to me. Differential Revision: https://phab.mercurial-scm.org/D6755

rust-dirstate: remove test case for DirsMultiset::new(Manifest, Some) It's no longer possible.

rust-dirstate: split DirsMultiset constructor per input type Since skip_state only applies to dirstate, it doesn't make sense to unify these constructors and dispatch by enum.

rust-dirstate: remove excessive clone() of parameter and return value I think pass-by-ref is preferred in general.

rust-dirstate: handle invalid length of p1/p2 parameters It uses match syntax since map_err() failed to deduce the argument type.

rust: simply use TryInto to convert slice to array Since our rust module depends on TryInto, there's no point to avoid using it. While rewriting copy_into_array(), I noticed CPython interface doesn't check the length of the p1/p2 values, which is marked as TODO.

rust-dirstate: use PARENT_SIZE constant where appropriate

rust-dirstate: rename NULL_REVISION to NULL_ID which isn't a revision number

rust-dirstate: remove repetition in array literal

rust-dirstate: remove too abstracted way of getting &[u8]

rust-dirstate: remove unneeded "ref" At 7cae6bc29ff9, .to_owned() was rewritten as .to_owned().to_vec(), which is no longer needed since the filename is a single reference.

rust-parsers: fix unboxing of PyInt on Python 3 Broken at 7cae6bc29ff9.

revlog: split `rawtext` retrieval out of _revisiondata This part is reasonably independent. Having it on its own clarify the code flow and will help code that inherit from revlog to overwrite specific area only.

revlog: avoid caching raw text too early in _revisiondata Without this change, we could cache the rawtext without considering for it validating the cache or not. If the exception raised by the invalid hash were to be caught and the same revision accessed again, the invalid rawtext would be returned.

revlog: add some documentation to `_revisiondata` code

revlog: move `nullid` early return sooner in `_revisiondata` Let us deal with the special case before we start dealing with more generic case.

revlog: stop calling `basetext` `rawtext` in _revisiondata If the cache entry is used as a base test for delta, it is not the rawtext we need. We update the variable name to clarify this.

revlog: assign rawtext earlier in `_revisiondata` Assigning the revision earlier make the code easier to read.

revlog: drop silly `raw` parameter to `rawdata` function This is a leftover from `revision` and does not make sense for `rawdata`

perf: don't depend on pycompat for older Mercurial versions We already define local _sysstr() and _xrange() for compatibility, so we should use those. Also create a similar local _bytestr() corresponding to pycompat.bytestr(). Differential Revision: https://phab.mercurial-scm.org/D6745

perf: don't try to call `util.queue` on Mercurial version before it existed Differential Revision: https://phab.mercurial-scm.org/D6744

perf: handle NameError for `pycompat.foo` when pycompat wasn't imported On old Mercurial versions, we won't have a pycompat variable defined, and then `pycompat.foo` will raise a NameError. Differential Revision: https://phab.mercurial-scm.org/D6743

rawdata: update callers in shallowbundle We update callers incrementally because this help bisecting failures. This was useful during development, so we expect it might be useful again in the future.

rawdata: update callers in storageutils We update callers incrementally because this help bisecting failures. This was useful during development, so we expect it might be useful again in the future.

rawdata: update callers in delta utils We update callers incrementally because this help bisecting failures. This was useful during development, so we expect it might be useful again in the future.

rawdata: update callers in repository We update callers incrementally because this help bisecting failures. This was useful during development, so we expect it might be useful again in the future.

rawdata: update callers in testing/storage.py We update callers incrementally because this help bisecting failures. This was useful during development, so we expect it might be useful again in the future.

rawdata: update callers in test-revlog-raw We update callers incrementally because this help bisecting failures. This was useful during development, so we expect it might be useful again in the future.