We are not passing the same args to merge strategies when we are doing an
--interactive rebase as we do with a --merge rebase. The merge strategy
should not need to be aware of which type of rebase is in effect. Add a
testcase which checks for the appropriate args.
Signed-off-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>