tests: add a comment that we're purposely testing py2 extension attributes Avoid someone unknowingly removing test coverage. There are tests for a properly byteified `testedwith` a few lines down. I don't see similar for `buglink`, but it's a trivial conversion to bytes, so I'm not concerned about testing the expected/wanted extension state. Differential Revision: https://phab.mercurial-scm.org/D9434

extensions: avoid a crash when the version isn't properly byteified on py3 We already force bytestr on the `testedwith` and `buglink` attributes in dispatch.py when generating a bug report with a similar comment about not every extension being ported to py3. We should do the same here, so the function can be properly typed. Differential Revision: https://phab.mercurial-scm.org/D9433

formatting: drop a few extra double quotes in docstrings These were made obvious by the reformatting in D9430. Differential Revision: https://phab.mercurial-scm.org/D9432

copies: introduce the hg-cpython wrapper for `combine_changeset_copies` This patch focus on the `hg-cpython` part of this work. Bridging the python code with the new rust code in `hg-core`. The next patch will actually plug this in the python code. The rust code use multiple Python callback, python related error within this callback are not expected unless they are a programming error or a data corruption. In addition, these callback will slowly be replaced by native Rust code. For these reasons, we use will deal with unexpected error within this callback using rust Panic and let the `rust-cpython` layer deal with raising a Python exception. The code dealing with the ChangedFile instance is repeating itself a lot. I did not factor these duplication out because that whole code will get replaced by entirely different one in a handful of changesets. Differential Revision: https://phab.mercurial-scm.org/D9298

copies: introduce a basic Rust function for `combine_changeset_copies` This new function mirror the python code. This first implementation does a lot of data copies and is therefore quite slow. However my goal here is to create a simple "frame" from where to start adding optimization. This patch focus on the `hg-core` part of this work. Coming patches will do the necessary `hg-cpython` work to be able to use this from Python. Differential Revision: https://phab.mercurial-scm.org/D9297

hghave: adjust the detection of `pylint` for modern versions I have pylint 2.6.0 installed locally, and it only has a single space. I have no idea when this changed. Differential Revision: https://phab.mercurial-scm.org/D9431