Some time ago we changed git-log in a massive way, and one consequence is
that the keyword changed. Adjust patch-id for that.

[jc: as Linus suggests, allowing both old and new prefix.]
Signed-off-by: NJohannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: NJunio C Hamano <junkio@cox.net>