This is shorter, makes the logic a bit easier to follow, and is
perhaps a bit faster too.

The logic is to make the final decision only when "subject" is there,
its early part matches "match", and the match is at the slash
boundary (or the whole thing).
Signed-off-by: NChristian Couder <chriscool@tuxfamily.org>
Reviewed-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>