sequencer: preserve commit messages

sequencer: preserve commit messages

sequencer calls "commit" with default options, which implies
"--cleanup=default" unless the user specified something else in their
config. This leads to cherry-picked commits getting a cleaned up commit
message, which is usually not an intended side-effect.

Make the sequencer use "--cleanup=verbatim" so that it preserves commit
messages independent of the default, unless the user has set config for "commit"
or the message is amended with -s or -x.

Reported-by: Christoph Anton Mitterer <calestyo@scientia.net>
Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>