In case 'git cherry-pick -s <commit>' failed, the user had to use 'git
commit -s' (i.e. state the -s option again), which is easy to forget
about. Instead, write the signed-off-by line early, so plain 'git
commit' will have the same result.
Also update 'git commit -s', so that in case there is already a relevant
Signed-off-by line before the Conflicts: line, it won't add one more at
the end of the message. If there is no such line, then add it before the
the Conflicts: line.
Signed-off-by: Miklos Vajna <vmiklos@suse.cz> Signed-off-by: Junio C Hamano <gitster@pobox.com>