The lien created by this act shall, after June 7, 1939, have priority over all other liens except taxes or special assessments whether or not the other liens accrued or were recorded before the accrual of the water or sewage system lien created by this act. However, this act shall not apply if a lease has been legally executed, containing a provision that the lessor shall not be liable for payment of water or sewage system bills accruing subsequent to the filing of the affidavit provided by this section. An affidavit with respect to the execution of a lease containing this provision shall be filed with the board, commission, or other official in charge of the water works system or sewage system, or both, and 20 days' notice shall be given by the lessor of any cancellation, change in, or termination of the lease. The affidavit shall contain a notation of the expiration date of the lease.