branchcache: simplify the branch rev cache test
We don't need that many content dump and this gets in the way in change in
access pattern (e.g. accessing revision in a different order change the order of
branches in the "names" file).
So we simplify this test in advance.
#!/usr/bin/env python3
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)