import: use gpatch if present on system. patch is broken on solaris.
fixes issue 205.
add new useful function, util.find_in_path.
# 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