util: add prefix to PrefixMatch The upstream match object now has a prefix function. Let's add it to our PrefixMatcher. The upstream implementation will return False if anypats() is true, which it is for our PrefixMatcher, so we go ahead and return False. This was caught by the tests failing.

include Makefile hgsubversion/help/*.rst tests/fixtures/invalid_utf8.tar.gz
recursive-include tests *.py *.sh *.svndump *.txt