The legislative authority of a city or town which has any outstanding warrants or bonds issued for the purpose of purchasing, acquiring, or constructing any such public utility or for making any additions or betterments thereto or extensions thereof, whether the warrants or bonds are general obligation warrants or bonds of the municipality or are payable solely from a special fund, into which fund the city or town is bound and obligated to set aside and pay any proportion or part of the revenue of the public utility, for the purchase, acquisition, or construction of which utility or the making of any additions and betterments thereto or extensions thereof such outstanding warrants or bonds were issued, may, without submitting the matter to the voters, provide for the issuance of funding or refunding bonds with which to take up, cancel, retire, and refund such outstanding warrants or bonds, or any part thereof, at maturity thereof, or before the maturity thereof, if they are subject to call for prior redemption.