amend: add config option to update time to current in hg amend (issue5828) The given config option i.e. `rewrite.update-timestamp` updates date to current when //True//. However when only date is to be updated to current with the working directory clean and no other attributes changing then it does not amend as stated in issue 5828. Further when `--date` flag is specified along with the new config option then `--date` is given priority over the config option. Differential Revision: https://phab.mercurial-scm.org/D5491

tests: correct version check in clientreactor test Experimentally, `(3, 6, 3)` is less than `sys.version_info` on an actual Python 3.6.3 installation. Let's just check `< (3, 6, 4)` instead of `<= (3, 6, 3)` so we stop seeing this bogus failure. Differential Revision: https://phab.mercurial-scm.org/D5502

py3: buildbot spotted more passing tests Differential Revision: https://phab.mercurial-scm.org/D5501

tests: add lots of b prefix goo to test-fastannotate-revmap.py All the paths are now bytes, so now things work correctly. # skip-blame just bytes/str issues in this test Differential Revision: https://phab.mercurial-scm.org/D5500

fastannotate: add a missing b prefix Spotted while debugging a test failure, but this wasn't the problem. # skip-blame b prefix Differential Revision: https://phab.mercurial-scm.org/D5499

rust-cpython: using the new bindings from Python The Python callers detect if we have cpython or direct-ffi bindings and fallback to the Python implementation if none is present. This intermediate state allows to compare the three possibilities. Differential Revision: https://phab.mercurial-scm.org/D5442

rust-cpython: binding for LazyAncestors The `mercurial.rustext.ancestor` module will not in the foreseeable future be a drop-in replacement for the pure `mercurial.ancestor`, because the Rust variants take the index at instantiation whereas the Python ones take a parents function. From the Python side, using the index from `ancestor` would leak internal details out of `mercurial.revlog`, and that's unwanted. Therefore, given that classes defined in `rust-cpython` have the same names in both language, we keep the Rust naming convention (CamelCase). Eventually, though, the ancestor module can be placed under control of `mercurial.policy`, but it will still be up to `revlog` to be aware of that and play the role of a factory for instantiation. Differential Revision: https://phab.mercurial-scm.org/D5441

discovery: move common heads computation inside partialdiscovery object This remove one of the private attribute access. In additions, head tracking and computation is a typical operation we can speed up using Rust.

discovery: introduce a partialdiscovery object This object will ultimately gather the data about common, undecided and missing revs in a single place and deal with most graph related computations. The goal is both to clarify the algorithm and to help provides a simple and clear API that can be reimplemented in Rust. For now, we only moved the `common` set in the object. In this commit, some direct access to the "private" `disco._common` attribute persist. They have not been removed yet because we won't need to expose a full API identical to `incrementalmissingancestors` and it seems simpler to access the attribute directly until the replacement is in place.

discovery: move handling of sampling special case inside sampling function The handling of cases where the number of revisions to sample is smaller than the sample size can be moved with the sample function themselves. This simplifies main logic, preparing a coming refactoring.