tests/readlink.py

tests: add test for issue5678

In addition to a test case for the direct problem described in the bug
report, this also adds a test case showing how obsmarkers can also get
lost when not using generaldelta.

Differential Revision: https://phab.mercurial-scm.org/D714

#!/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)