.arcconfig

typing: add some type annotations to mercurial/phases.py

Some of these were helpful in typing other modules, and then I typed the
easy-ish ones.  Black forces the long `Phasedefaults` definition to be wrapped,
which pytype seems OK with (as shown with `reveal_type()`), but it does seem to
confuse PyCharm a bit.

Differential Revision: https://phab.mercurial-scm.org/D10126

{
    "conduit_uri": "https://phab.mercurial-scm.org/api",
    "phabricator.uri": "https://phab.mercurial-scm.org/",
    "repository.callsign": "HG",
    "arc.land.onto.default": "@",
    "base": "hg:.^"
}