tests/readlink.py

copies: replace duplicatecopies() by function that takes contexts

The callers mostly have context objects, so let's avoid looking up the
same context objects inside `duplicatecopies()`.

I also renamed the function to `graftcopies()` since I think that
better matches its purpose. I did it in the same commit so it's easier
for extensions to switch between the functions.

Differential Revision: https://phab.mercurial-scm.org/D7858

#!/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)