view hgext/hooklib/reject_new_heads.py @ 51730:63ede7a43a37 stable

demandimport: don't delay threading import

A recent cpython change breaks demandimport by importing threading
locally in importlib.util.LazyLoader.exec_module; add it (plus warnings
and _weakrefset, which are imported by threading) to demandimport's
ignore list.

```
Traceback (most recent call last):
  File "/usr/bin/hg", line 57, in <module>
    from mercurial import dispatch
  File "<frozen importlib._bootstrap>", line 1360, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1331, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 935, in _load_unlocked
  File "/usr/lib/python3/dist-packages/hgdemandimport/demandimportpy3.py", line 52, in exec_module
    super().exec_module(module)
  File "<frozen importlib.util>", line 257, in exec_module
  File "<frozen importlib._bootstrap>", line 1360, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1331, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 935, in _load_unlocked
  File "/usr/lib/python3/dist-packages/hgdemandimport/demandimportpy3.py", line 52, in exec_module
    super().exec_module(module)
  File "<frozen importlib.util>", line 267, in exec_module
AttributeError: partially initialized module 'threading' has no attribute 'RLock' (most likely due to a circular import)
```

Ref: https://github.com/python/cpython/issues/117983
     https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1076449
     https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1076747

# Copyright 2020 Joerg Sonnenberger <[e-mail]>
#
# 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 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)
            )