typing: add `from __future__ import annotations` to most files
Now that py36 is no longer supported, we can postpone annotation evaluation.
This means that the quoting is usually optional (for things imported under the
guard of `if typing.TYPE_CHECKING:` to avoid circular imports), and there's less
overhead on startup[1].
There may be some missing here. I backed out 6000f5b25c9b (which removed the
`from __future__ import ...` that was supporting py2), reverted the changes in
`contrib/`, `doc/`, and `tests/`, and then ran:
$ hg status -n --change . | \
xargs sed -i -e 's/from __future__ import .*$/from __future__ import annotations/'
There were some minor tweaks needed when reviewing (mostly making the spacing
around the import consistent, and `mercurial/testing/__init__.py` had a
multiline import that wasn't fully rewritten.
[1] https://docs.python.org/3/whatsnew/3.7.html#pep-563-postponed-evaluation-of-annotations
# Copyright 2020 Joerg Sonnenberger <joerg@bec.de>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
"""reject_new_heads is a hook to check that branches touched by new changesets
have at most one open head. It can be used to enforce policies for
merge-before-push or rebase-before-push. It does not handle pre-existing
hydras.
Usage:
[hooks]
pretxnclose.reject_new_heads = \
python:hgext.hooklib.reject_new_heads.hook
"""
from __future__ import annotations
from mercurial.i18n import _
from mercurial import (
error,
pycompat,
)
def hook(ui, repo, hooktype, node=None, **kwargs):
if hooktype != b"pretxnclose":
raise error.Abort(
_(b'Unsupported hook type %r') % pycompat.bytestr(hooktype)
)
ctx = repo.unfiltered()[node]
branches = set()
for rev in repo.changelog.revs(start=ctx.rev()):
rev = repo[rev]
branches.add(rev.branch())
for branch in branches:
if len(repo.revs("head() and not closed() and branch(%s)", branch)) > 1:
raise error.Abort(
_(b'Changes on branch %r resulted in multiple heads')
% pycompat.bytestr(branch)
)