rust-chg: suppress panic while writing chg error to stderr Otherwise "chg >/dev/full 2>&1" would exit with 101. Spotted by test-basic.t.

logcmdutil: add a helpful assertion to catch mistyped templates early This would have made a defect in test-notify.t much easier to figure out. Differential Revision: https://phab.mercurial-scm.org/D5097

notify: adapt to new location of email module's errors Differential Revision: https://phab.mercurial-scm.org/D5099

notify: add some b prefixes # skip-blame just b prefixes Differential Revision: https://phab.mercurial-scm.org/D5098

py3: fix test-diff-color.t Differential Revision: https://phab.mercurial-scm.org/D5095

py3: fix test-revlog.t The mpatchError has a trailing comma on Python 2 but not on Python 3, so use a glob to handle both Python 2 and Python 3. Differential Revision: https://phab.mercurial-scm.org/D5093

fuzz: try *even harder* to prevent Python from looking up usernames Differential Revision: https://phab.mercurial-scm.org/D5092

wireproto: fix incorrect function name in docstring The docstring for `iwireprotocolcommandcacher` references an `onoutputfinished` method. The actual name of the function is `onfinished`. Differential Revision: https://phab.mercurial-scm.org/D5090

py3: fix test-status.t Differential Revision: https://phab.mercurial-scm.org/D5089

formatter: make debug output prettier "(glob)" won't be needed since pprintgen() can print dict items in stable order.

stringutil: allow to specify initial indent level of pprint() I want to pprint() an inner object, which starts with level=1 indent.

stringutil: make level parameter of pprintgen() 0-origin I think this makes more sense in that the level is incremented where nesting goes one more deep.

formatter: use stringutil.pprint() in debug output to drop b''

rust: exposing in parsers module To build with the Rust code, set the HGWITHRUSTEXT environment variable. At this point, it's possible to instantiate and use a rustlazyancestors object from a Python interpreter. The changes in setup.py are obviously a quick hack, just good enough to test/bench without much refactoring. We'd be happy to improve on that with help from the community. Rust bindings crate gets compiled as a static library, which in turn gets linked within 'parsers.so' With respect to the plans at https://www.mercurial-scm.org/wiki/OxidationPlan this would probably qualify as "roll our own FFI". Also, it doesn't quite meet the target of getting rid of C code, since it brings actually more, yet: - the new C code does nothing else than parsing arguments and calling Rust functions. In particular, there's no complex allocation involved. - subsequent changes could rewrite more of revlog.c, this time resulting in an overall decrease of C code and unsafety.

rust: iterator bindings to C code In this changeset, still made of Rust code only, we expose the Rust iterator for instantiation and consumption from C code. The idea is that both the index and index_get_parents() will be passed from the C extension, hence avoiding a hard link dependency to parsers.so, so that the crate can still be built and tested independently. On the other hand, parsers.so will use the symbols defined in this changeset.