Some systems don't return 1 from regexec() when the pattern does not
match (notably HP-UX which returns 20).
Bug identified by Dscho and H.Merijn Brand.
Signed-off-by: Björn Steinbrink <B.Steinbrink@gmx.de> Tested-by: H.Merijn Brand <h.m.brand@xs4all.nl> Cc: Johannes Schindelin <Johannes.Schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>