Any ordinance which, in accordance with the provisions of Article III, Section 7, of this Charter, shall have gone into effect prior to the filing of a referendum petition thereon shall be subject to referendum as in the case of other ordinances, and further action thereunder shall be suspended from the date of the secretary’s certification to the commission that a sufficient referendum petition has been filed. If, when submitted to a vote of the voters, any such ordinance be not approved by a majority of those voting thereon it shall be considered repealed and all rights and privileges conferred by it shall be null and void except that any ordinance so repealed shall be deemed sufficient authority for any payments made or expenses incurred in accordance therewith prior to the date of the secretary’s certification to the commission that a sufficient referendum petition has been filed, provided that the repeal of any such ordinance by referendum shall not affect any bona fide contract previously entered into by the city under authority of such ordinance prior to the date of said certification.