hgext/fsmonitor/pywatchman/compat.py

copies: move short-circuiting of dirstate copies out of _forwardcopies()

I'd like to move the filtering of copies we do after chaining to the
end of all chaining (in a single place in pathcopies()). One problem
that came up when trying that was that we allow things like `hg cp -f
<file> <existing file>` so the user can later amend that in. Filtering
at the end would mean that we remove those copies. That would break
`hg st -C`. This patch therefore moves the short-circuiting of
dirstate copies into pathcopies() so we can more easily handle the
dirstate-only case differently.

I initially thought this might change some behavior when the user does
`hg status --rev 'wdir()' --rev .` during an uncommitted merge, since
_backwardrenames() would reverse the copies in that case. However, I
couldn't come up with a test case where it made a difference.

Differential Revision: https://phab.mercurial-scm.org/D6600

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from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
# no unicode literals

'''Compatibility module across Python 2 and 3.'''

import sys

PYTHON3 = sys.version_info >= (3, 0)

# This is adapted from https://bitbucket.org/gutworth/six, and used under the
# MIT license. See LICENSE for a full copyright notice.
if PYTHON3:
    def reraise(tp, value, tb=None):
        try:
            if value is None:
                value = tp()
            if value.__traceback__ is not tb:
                raise value.with_traceback(tb)
            raise value
        finally:
            value = None
            tb = None
else:
    exec('''
def reraise(tp, value, tb=None):
    try:
        raise tp, value, tb
    finally:
        tb = None
'''.strip())

if PYTHON3:
    UNICODE = str
else:
    UNICODE = unicode