Unless otherwise agreed, a landlord who conveys premises that include a dwelling unit subject to a rental agreement in a good faith sale to a bona fide purchaser is relieved of liability under the rental agreement and this chapter as to events occurring subsequent to notice to the tenant of the conveyance. Unless otherwise agreed, a managing agent of premises that includes a dwelling unit is relieved of liability under the rental agreement and this chapter as to events occurring after written notice to the tenant of the termination of his management.