rewriteutil: handle dropped commits when updating description hashes In looking to leverage this with the absorb extension, the old -> new mapping there allows the new value to be None. We could filter that out and not pass it to this method, but it seems worth a message to the user. (I wonder if these should be an info or warning, because it's unlikely people are using `-v` regularly.) Differential Revision: https://phab.mercurial-scm.org/D9181

dirstate-tree: move a conditional in an explicit boolean This will help readability a bit and make the next change simpler to read. Differential Revision: https://phab.mercurial-scm.org/D9202

rust: cleanup some white space in a dock They seems to have sneaked there somehow. Differential Revision: https://phab.mercurial-scm.org/D9201

commit: pass ChangingFiles object as argument to _process_files Instead of returning it, we pass it as an argument. This makes the whole if-else in `_prepare_files` a bit simpler. Else each if-else branch was creating the object. Differential Revision: https://phab.mercurial-scm.org/D9194

commit: pass mergestate into `_process_files` instead of re-reading it Differential Revision: https://phab.mercurial-scm.org/D9193

commit: move salvaged calculation a bit earlier in the function This helps us initialize mergestate before and now we can pass it into `_process_files()` instead of re-reading it there. Differential Revision: https://phab.mercurial-scm.org/D9192

commit: refactor salvage calculation to a different function Differential Revision: https://phab.mercurial-scm.org/D9191

tests: run test-copies-chain-merge.t also with copies in changesets We have these tests already and it seems like a waste to not run them in the changesets case. The biggest differences stem from `hg log --follow` not working with copies stored in the changeset extras. Differential Revision: https://phab.mercurial-scm.org/D9173

tests: add test of copies suggested by Pierre-Yves on D9159 Differential Revision: https://phab.mercurial-scm.org/D9171

tests: update test-copies-chain-merge.t to not use empty files Merging empty files is not very interesting or realistic. Differential Revision: https://phab.mercurial-scm.org/D9172

revset: fix sorting key of wdir revision It would go wrong on Python 2, and would crash on Python 3.

grep: move prep() to grepsearcher class

grep: move readfile() to grepsearcher class

grep: move getbody() to grepsearcher class

grep: add stub class that maintains cache and states of grep operation Prepares for extracting stateful functions from commands.grep().

grep: move match and diff logic to new module commands.grep() has lots of functions and classes. Let's split it into reusable components so we can leverage them to implement a revset predicate for 'hg grep --diff'. I want to do 'hg log -r "diff(pattern)"'.

grep: explicitly pass regexp to closure functions These functions will be extracted to new module.

upgrade: improve documentation of matchrevlog() It was not clear what selected for cloning meant. I updated with an extra line of description.

automation: support running against Python 3.9 We just added CPython 3.9.0 to the automation environment. Let's support actions targeting it. One side-effect of this change is that we'll produce Windows wheels for Python 3.9 by default. This is desirable. Differential Revision: https://phab.mercurial-scm.org/D9189

automation: upgrade packages in Linux environment It's been a while since we've ran `pip-compile -U`. Let's do that. When I ran this command, black was upgraded and newer versions of black complains about formatting differences. I didn't feel like shaving a yak, so I pinned the current black version to avoid churn. I manually ran tests against all major Python versions and I'm fairly certain no new test failures were introduced. Differential Revision: https://phab.mercurial-scm.org/D9188

packaging: upgrade packages in Windows environment I ran `pip-compile -U` to update all packages to latest versions. I did this so the Windows environment is more modern. dulwich 0.20 dropped support for Python 2.7. Rather than add yet another requirements.txt file, I decided to just pin at an older release to minimize complexity. Differential Revision: https://phab.mercurial-scm.org/D9187

contrib: install Python 3.9.0 We update the Windows and Linux environments to install CPython 3.9.0, which was released a few days ago. Differential Revision: https://phab.mercurial-scm.org/D9186

contrib: stop installing Python 3.5 and 3.6 in Windows environment We're only publishing Python 3.7+ wheels and other builds on Windows. Python 3.5 and 3.6 are not supported on this platform. Let's stop installing them in the development environment. Differential Revision: https://phab.mercurial-scm.org/D9185

py3: convert an exception message to bytes One of our users ran into this (unrelated to my recent work on more specific errors). Differential Revision: https://phab.mercurial-scm.org/D9184