No bonds, notes or other evidences of indebtedness heretofore issued by authorities incorporated under the Municipality Authorities Act, approved June 28, 1935, (Pamphlet Laws, four hundred sixty-three), as amended and supplemented, shall be invalid by reason of the fact that any member of the board or any officer of said authority was, at the time of the issuance of such bonds, notes or other evidences of indebtedness, a member or officer of the governing body of the incorporating municipality or municipalities or an officer thereof, provided that such bonds, notes or other evidences of indebtedness are otherwise valid.
53 P.S. § 371