The state auditor need not register, certify, nor sign revenue obligations after July 26, 1981. These obligations shall be held in every action, suit, or proceeding in which their validity is or may be brought into question prima facie valid and binding obligations of the districts in accordance with their terms, notwithstanding any defects or irregularities in the proceedings for the organization of the district and the election of the commissioners thereof or for the authorization and issuance of such revenue obligations or in the sale, execution, or delivery thereof.