byteify-strings: add space in special comments to silence flake8 error This is done soon enough that nobody has had the time to use this feature yet.

revset: drop argument when it's None getstack's definition is `getstack(repo, rev=None)`, so providing None explicitly is unnecessary. Moreover, when x is not None, it's definitely not a revision but a part of a parsed tree of revset arguments. Differential Revision: https://phab.mercurial-scm.org/D6707

stack: remove unnecessary reverse() predicate Stack already sorts revisions, so no need to do it twice. This change was a part of D2400, which didn't land for other reasons. See also D2399, where this change was suggested. Differential Revision: https://phab.mercurial-scm.org/D6706

automation: increase root volume size on Linux It is close to full in the AMI. I actually ran out of space running tests without increasing the volume size! Differential Revision: https://phab.mercurial-scm.org/D6716

automation: install Rust in Linux environment This will install Rust 1.31.1, 1.34.2, and whatever stable is at the time the install runs. We install 1.31.1 as our minimum supported Rust version (I think that's what we're currently targeting) and 1.34 because that's what Debian 10 is shipping. Differential Revision: https://phab.mercurial-scm.org/D6715

automation: update packages in requirements files We like keeping up to date. The content of the autogenerated files changed slightly because I used a newer version of `pip-compile` than what was used previously. Differential Revision: https://phab.mercurial-scm.org/D6714

automation: install latest Python versions This required bumping the pyenv commit so the new versions are available. Differential Revision: https://phab.mercurial-scm.org/D6713

upgrade: introduce the internal code for revlog cloning selection For now we still clone every single revlogs but all the selection mechanism is now in place in the lower layer. The next changesets will introduce the user interface part of the selection.

upgrade: introduce a _copyrevlog method This function copies a revlog from the old store to the new one, without re-adding all deltas manually. This will eventually save a lot of time when some revlog does not needs any conversions. Code actually using this will be introduced in later changesets.

upgrade: rename `_copyrevlogs` to `_clonerevlogs` The underlying revlog method is named `clone`, keeping the naming consistent seems clearer. This is motivated to clarify the difference with an (upcoming) function that simply copy revlog files as is.

upgrade: walk the source store file only once I don't expect this to have a significant performance impact, but it seems simpler and saner to do the operation only once and to keep the result around.

upgrade: always use full text if "full-add" mode is enable We should not be using a delta since the goal is to perform a full addition from scratch in all cases. Without this patch, `hg debugupgraderepo --optimize re-delta-fulladd --run` can crash.

byteify-strings: fix misalignment with multi-line parenthesis This improves the current fix to also take into account cases where the last line ended on the opening `(`, `[` or `{` and adds a regression test.

byteify-strings: add test for byteify-strings.py This tests the basic features expected from this script, some cases may not be covered yet. A future patch will demonstrate an issue with multi-line `(`, `[` and `{` alignment and propose a fix.

merge with stable