cmd_rebase() and cmd_rebase__interactive() used different enums to hold
the current action. Change to using a common enum so the values are the
same when we change `rebase -i` to avoid forking `rebase--interactive`.
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk> Signed-off-by: Junio C Hamano <gitster@pobox.com>