mercurial/txnutil.py

bookmarks: use correct store for "ambiguity check"

I still don't quite know what the check does, but I clearly got it
wrong in 526750cdd02d (bookmarks: keep bookmarks in .hg/store if new
config set, 2019-05-15). Just compare with the strings we use in
@repofilecache and @storecache. These bugs were then copied to the
stable branch in c2b83c957621 (localrepo: grab mixedrepostorecache
class from 526750cdd02d, 2019-05-20) and 2338bdea4474 (bookmark: also
make bookmark cache depends of the changelog, 2019-05-20). As a
result, test-wireproto-exchangev2.t is flaky on both branches. This
patch fixes that.

Differential Revision: https://phab.mercurial-scm.org/D6469

# txnutil.py - transaction related utilities
#
#  Copyright FUJIWARA Katsunori <[e-mail]> and others
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from __future__ import absolute_import

import errno

from . import (
    encoding,
)

def mayhavepending(root):
    '''return whether 'root' may have pending changes, which are
    visible to this process.
    '''
    return root == encoding.environ.get('HG_PENDING')

def trypending(root, vfs, filename, **kwargs):
    '''Open  file to be read according to HG_PENDING environment variable

    This opens '.pending' of specified 'filename' only when HG_PENDING
    is equal to 'root'.

    This returns '(fp, is_pending_opened)' tuple.
    '''
    if mayhavepending(root):
        try:
            return (vfs('%s.pending' % filename, **kwargs), True)
        except IOError as inst:
            if inst.errno != errno.ENOENT:
                raise
    return (vfs(filename, **kwargs), False)