upload-pack would set create_full_pack=1 if nr_has==0, but would ask later
if nr_needs<MAX_NEEDS. If that proves true, it would ignore create_full_pack,
and arguments would be written into unreserved memory.
Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de> Signed-off-by: Junio C Hamano <junkio@cox.net>