The city council may, at any time prior to the execution of any contract with the city, require the contractor to execute to the city a bond, in such amount as the council may require, conditioned for the faithful performance of such contract; which bond shall be signed by two (2) sureties satisfactory to the council, who shall justify in double the amount of such bond over and above all statutory liabilities or a surety bond. (Prior code § 14102)