tests/readlink.py

reachableroots: default to the C implementation

This patch is part of a series of patches to speed up the computation of
revset.reachableroots by introducing a C implementation. The main motivation is to
speed up smartlog on big repositories. At the end of the series, on our big
repositories the computation of reachableroots is 10-50x faster and smartlog on is
2x-5x faster.

Before this patch, reachableroots was computed in pure Python by default. This
patch makes the C implementation the default and provides a speedup for
reachableroots.

#!/usr/bin/env python

import errno, os, 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, 'not a symlink'

sys.exit(0)