git p4: standardize submit cancel due to unchanged template

git p4: standardize submit cancel due to unchanged template

When editing the submit template, if no change was made to it,
git p4 offers a prompt "Submit anyway?".  Answering "no" cancels
the submit.

Previously, a "no" answer behaves like a "[s]kip" answer to the
failed-patch prompt, in that it proceeded to try to apply the
rest of the commits.  Instead, put users back into the new
"[s]kip / [c]ontinue" loop so that they can decide.  This makes
both cases of patch failure behave identically.

The return code of git p4 after a "no" answer is now the same
as that for a "skip" due to failed patch; update a test to
understand this.

Signed-off-by: Pete Wyckoff <pw@padd.com>
Acked-by: Luke Diamand <luke@diamand.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>