* build-packet.c (write_header2): If a suggested header length is provided
along with a zero length, interpret this as an actual zero length packet
and not as an indeterminate length packet. (do_comment, do_user_id): Use
it here as these packets might be naturally zero length.
* parse-packet.c (parse): Show packet type when failing due to an
indeterminate length packet.
* misc.c (parse_options): Only provide args for the true (i.e. not
"no-xxx") form of options.