t9902 had a list of three random porcelain commands as a sanity check,
one of which was filter-branch. Since we are recommending people not
use filter-branch, let's update this test to use rebase instead of
filter-branch.
Signed-off-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>