mercurial/txnutil.py

copies: always respect matcher arg to _forwardcopies()

The function would ignore the matcher if the dirstate copies were
requested. It doesn't matter in practice because all callers used the
returned map only for looking up specific files from and those files
had already been filtered by the matcher (AFACT). Still, it's a little
confusing, so let's make it clearer by respecting the matcher in this
case too.

Differential Revision: https://phab.mercurial-scm.org/D1695

# 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)