Where any school district in any borough or township has heretofore issued bonds or other evidences of indebtedness, without having first submitted the question of increasing the indebtedness to the electors of the district, when such submission was made necessary by law, such bonds or other evidences of indebtedness shall be returned and canceled before the issuance of other bonds or evidences of indebtedness made valid by such election as hereinbefore prescribed.
24 P.S. § 524