Add the options --committer-date-is-author-date and --ignore-date
to git-rebase. They were introduced in commit a79ec62d0 for git-am.
These options imply --force-rebase.
Signed-off-by: Michele Ballabio <barra_cuda@katamail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>