commit does not always succeed, so we'll have to check for
it in the absence of set -e. This fixes a regression
introduced in 9e4bc7dd1bb9d92491c475cec55147fa0b3f954d
Signed-off-by: Eric Wong <normalperson@yhbt.net> Signed-off-by: Junio C Hamano <junkio@cox.net>