Whenever bonds for refunding and bonds for any other purposes allowed by the Institution Bond Act are issued in combination, the lien of the refunding bonds on income from the permanent fund and on the income and current fund is not prior or superior to any lien on these sources to secure payment of the bonds retired and refunded, or to any lien on them to secure payment of any outstanding bonds payable from them, except as provided in each resolution authorizing issuance of the outstanding bonds which are not being retired and refunded.