(a) It shall not be a defense in favor of any surety on any bond or obligation that he or she became surety thereon on the condition that the principal obligor should procure the cosuretyship of other persons before the instrument should be delivered. This shall be the case whether the names of the contemplated cosureties appear upon the face of the instrument at the time the condition is stated or are specified in an independent agreement or understanding.
(b) In case of every failure to procure the joinder of the contemplated cosureties, the liability of the sureties who actually sign the bond or other obligation shall be as complete and valid as if no condition had been mentioned. The instrument to which their names are signed shall be deemed and taken to all intents and purposes as their obligation.