When git-am fails it's not always easy to see which patch failed,
since it's often hidden by a lot of error messages.
Add an extra line which prints the name of the failed patch just
before the resolve message to make it easier to find.
Signed-off-by: Jonas Flodén <jonas@floden.nu> Signed-off-by: Junio C Hamano <gitster@pobox.com>