> +static int parse_want_ref(const char *line, struct string_list *wanted_refs)
> +{
> + const char *arg;
> + if (skip_prefix(line, "want-ref ", &arg)) {
> + struct object_id oid;
> + struct string_list_item *item;
> + struct object *o;
> +
> + if (read_ref(arg, &oid))
> + die("unknown ref %s", arg);One more thing - if you're planning to "die" here, also write out an error to the user, just like in parse_want().

