tests/readlink.py

run-tests: produce error on running a failing test

This patch fixes a regression recently introduced by a refactoring (see
92a6b16c9186 and about 200 previous changesets from Gregory Szorc).  It produce
an error message everytime with a test filename which gets fail while testing
except at one condition when '--nodiff' option is enabled.

#!/usr/bin/env python

import errno, os, sys

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

sys.exit(0)