409. Duration of implied covenant.

The implied covenant for quiet enjoyment does not necessarily ensure the possession of the tenant during the whole term. It is operative only during the continuance of the landlord's estate by virtue of which he was able to give possession to the tenant; and, if this estate ceases during the currency of the term, the liability on the covenant, other than for disturbance already suffered, also ceases. Thus an undertenant for a term longer than the residue of the head term has no remedy if he is evicted at the expiration of the head term