Any coupons for the payment of interest on bonds of any district shall be considered for all purposes as warrants drawn upon the general fund of the district issuing such bonds, and when presented to the treasurer of the county having custody of the funds of such district at maturity, or thereafter, and when so presented, if there are not funds in the treasury to pay the coupons, it shall be the duty of the county treasurer to endorse the coupons as presented for payment, in the same manner as county warrants are indorsed, and thereafter the coupons shall bear interest at the same rate as the bonds to which they were attached. When there are no funds in the treasury to make interest payments on bonds not having coupons, the overdue interest payment shall continue bearing interest at the bond rate until it is paid, unless otherwise provided in the proceedings authorizing the sale of the bonds.