tests/readlink.py

phabricator: add debug logging to show previous node values in `phabsend`

This isn't real useful here, but was very useful showing how `phabsend --fold`
handles commits created by `hg fold` and `hg split`.  It introduces a new debug
function and flag instead of using `ui.debug()`, because `--debug` prints out
all of the API chatter.

Differential Revision: https://phab.mercurial-scm.org/D8389

#!/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)