tests/svn-safe-append.py

treemanifest: further optimize treemanifest.matches()

The matches function was previously traversing all submanifests to look for
matching files, even though it was possible to know if a submanifest won't
contain any matches.

This change adds a visitdir function on the match object to decide quickly if
a directory should be visited when traversing. The function also decides if
_all_ subdirectories should be traversed.

Adding this logic as methods on the match object also makes the logic
modifiable by extensions, such as largefiles.

An example of a command this speeds up is running
  hg status --rev .^ python/
on the Mozilla repo with the treemanifest experiment enabled.
It goes from 2.03s to 1.85s.

More improvements to speed from this change will happen when treemanifests are
lazily loaded. Because a flat manifest is still loaded and then converted
into treemanifests, speed improvements are limited.

This change has no negative effect on speed. For a worst-case example, this
command is not negatively impacted:
  hg status --rev .^ 'relglob:*.js'
on the Mozilla repo. It goes from 2.83s to 2.82s.

#!/usr/bin/env python

__doc__ = """Same as `echo a >> b`, but ensures a changed mtime of b.
Without this svn will not detect workspace changes."""

import sys, os

text = sys.argv[1]
fname = sys.argv[2]

f = open(fname, "ab")
try:
    before = os.fstat(f.fileno()).st_mtime
    f.write(text)
    f.write("\n")
finally:
    f.close()
inc = 1
now = os.stat(fname).st_mtime
while now == before:
    t = now + inc
    inc += 1
    os.utime(fname, (t, t))
    now = os.stat(fname).st_mtime