There are a variety of aspects that are common to all rebases regardless
of which backend is in use; however, the behavior for these different
aspects varies in ways that could surprise users. (In fact, it's not
clear -- to me at least -- that these differences were even desirable or
intentional.) Document these differences.
Signed-off-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>