view mercurial/txnutil.py @ 44805:02bf61bb4a70

copy: to find copy source, walk parent of revision we're marking copies in

As shown in the previous patch, `hg cp --after --at-rev . src dst`
fails if `src` is not in `.`. It seems obvious that you should always
walk the *parent* of the revision you're marking copies in, but that's
not how it was done for the working copy, and I didn't think to change
it when marking copies in a non-working-copy commit.

This patch fixes that by walking the parent commit instead, but only
if we're marking copies for a non-working-copy commit. We need to
leave the working-copy code unchanged because it depends on the weird
behavior of `workingctx.walk()`. With these changes, there's very
little overlap between the working-copy version and the
non-working-copy version of `walkpats()`, but I've refrained from
cleaning that up on the stable branch.

Differential Revision: https://phab.mercurial-scm.org/D8494

# 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(b'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(b'%s.pending' % filename, **kwargs), True)
        except IOError as inst:
            if inst.errno != errno.ENOENT:
                raise
    return (vfs(filename, **kwargs), False)