Except for the requirement of an ordinance and the right to referendum thereon, the amendments to Section 6547 adopted at the 1971 Regular Session of the Legislature shall not limit or affect any heretofore existing right of any public agency to be a party to a joint powers agreement which authorizes an entity to issue bonds under this article, including the right to accomplish a public purpose of such public agency regardless of whether such public agency is obligated to make any contribution or payment of public funds or property.