filterfiles: Search as long as the target is a prefix of current. filterfiles was failing to find files for directory arguments if another file existed that started with the directory name and sorted earlier. For example, a manifest of ('foo.h', 'foo/foo') would cause filterfiles('foo') to return nothing. This resolves issue #294.

# repo.py - repository base classes for mercurial
#
# Copyright 2005 Matt Mackall <mpm@selenic.com>
#
# This software may be used and distributed according to the terms
# of the GNU General Public License, incorporated herein by reference.

class RepoError(Exception): pass