There are no more direct calls to am_signoff(), so we can fold its
logic in am_append_signoff().
(This is done in a separate commit rather than in the previous one, to
make it easier to revert this specific change if additional calls are
ever introduced.)
Signed-off-by: Giuseppe Bilotta <giuseppe.bilotta@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>