405. Effect of qualified covenant.

The covenant usually provides for quiet enjoyment 'without interruption by the landlord or any persons rightfully claiming under or in trust for him' or 'without any lawful interruption by the landlord or any persons claiming under or in trust for him'. Whichever of these forms is used, the covenant protects only against the acts of persons claiming under the landlord so far as they are successors in title to the landlord, or have actual authority from him to do the acts1; and the effect is the same even if the words 'rightfully' or 'lawful' are not inserted in the