Notwithstanding the interest rate limitation set forth in section 1759 of this title prior to April 14, 1969, if any municipal corporation has prior to that date authorized bonds to bear interest at a rate of interest in excess of five percent, but not more than six percent, the authorization so voted is hereby ratified and confirmed and declared to be legal and valid, and such municipal corporation may issue such bonds at a rate of interest not exceeding the rate stated in the vote authorizing the issuance of the bonds. (Added 1969, No. 58, § 4, eff. April 14, 1969.)