tests/readlink.py

hg: recognize include and exclude patterns when cloning

This commit teaches clone() to accept arguments defining file
patterns to clone. This is the first step in teaching core code
about the existence of a narrow clone.

Right now, we only perform validation of the arguments and pass
additional options into createopts to influence repository
creation. Nothing of consequence happens with that creation option
yet, however.

For now, arbitrary restrictions exist, such as not allowing patterns
for shared repos and disabling local copies when patterns are
defined. We can potentially lift these restrictions in the future
once partial clone/storage support is more flushed out. I figure
it is best to reduce the surface area for bugs for the time being.

It may seem weird to prefix these arguments with "store." However,
clone is effectively pull + update and file patterns could apply to
both the store and the working directory. The prefix is there to
disambiguate in the future when this function may want to use
different sets of patterns for the store and working directory.

Differential Revision: https://phab.mercurial-scm.org/D4536

#!/usr/bin/env python

from __future__ import absolute_import, print_function

import errno
import os
import sys

for f in sys.argv[1:]:
    try:
        print(f, '->', os.readlink(f))
    except OSError as err:
        if err.errno != errno.EINVAL:
            raise
        print(f, '->', f, 'not a symlink')

sys.exit(0)