This option was added in 58794775 (rebase: implement
--[no-]autostash and rebase.autostash, 2013-05-12).
Completion of "--autosquash" has been there, but this was not;
addition of this would require people completing "--autosquash" to
type a bit more than before.
Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr> Signed-off-by: Junio C Hamano <gitster@pobox.com>