byteify-strings: add --treat-as-kwargs argument to handle kwargs-like objects This argument will help extensions move to Python 3 as keyword arguments should not be byte-prefixed. Most of the time, code bases will call this object `kwargs`, but other conventions exist like `opts`, so it should make sense to allow for custom names. This is a best effort solution that does minimal static checking; cases like `options = [o for o in ('a', 'b', 'c') if kwargs.get(o)]` and other just as complicated will not be detected.

byteify-strings: add helpers to check for item access or method call These helpers will be used in a future patch, split for ease of review.

byteify-strings: add support for ignore comments Our simple token analysis is sometimes not clever enough, we need to be able to turn off our script for parts of the code. This change introduces three special comments: - `#no-py3-transform` to tell `byteify-strings` ignore the next line - `#py3-transform: off` to ignore everything until the end of the file - `#py3-transform: on` to stop ignoring The last two can be particularly useful within Python 2/3 compatibility files.

byteify-strings: handle triple quoted strings if they are not docstrings As with anything in this script, this is a best effort approach. Most of the time, when a triple quoted string is assigned to something, it's not a docstring.

byteify-strings: handle multi-line strings in _ensuresysstr The current implementation did not handle calls like `repo.ui.log("first line" "other line")` correctly.

fix: run fixer tools in the repo root as cwd so they can use the working copy This lets fixer tools do things like find configuration files, with the caveat that they'll only see the version of that file in the working copy, regardless of what revisions are being fixed. Differential Revision: https://phab.mercurial-scm.org/D6440

config: add defaultvalue template keyword This patch tries to fix one of the issues mentioned in issue6014. This adds a new `defaultvalue` template keyword to be used with `hg showconfig` to get the default value of the config item. Differential Revision: https://phab.mercurial-scm.org/D6704

merge with stable

module-policy: update rust extension import to use the new module policy Differential Revision: https://phab.mercurial-scm.org/D6677

transaction: leave unfinished without crashing when not properly released I think the transaction.__del__ is there just as a last resort in case we (or an extension) forgot to release the transaction. When that happens, the repo can (or will on Python 3?) get deleted before the transaction. This leads to a crash in test-devel-warnings.t on Python 3 because we tried to access repo.dirstate, where repo was retried from a weak reference. There's not much we can do here, but let's at least avoid the crash. The user will have run `hg recover` afterwards regardless. Differential Revision: https://phab.mercurial-scm.org/D6664