Function option_parse_if_missing

builtin/interpret-trailers.c:42–47

}

static int option_parse_if_missing(const struct option *opt,
				   const char *arg, int unset UNUSED)
{
	/* unset implies NULL arg, which is handled in our helper */
	return trailer_set_if_missing(opt->value, arg);
}

static void new_trailers_clear(struct list_head *trailers)
{