This patch teaches git stash branch to tolerate stash-like arguments.
In particular, a stash is only required if an argument isn't specified
and the stash is only dropped if a stash entry reference was
specified or implied.
The implementation has been simplified by taking advantage of
assert_stash_like() and the variables established by
parse_flags_and_rev().
Signed-off-by: Jon Seymour <jon.seymour@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>