A covenant by the grantor in a deed “that he has the right to convey the said land to the grantee” , shall have the same effect as if the grantor had covenanted that he has good right, full power and absolute authority to grant, bargain, sell and convey the said land, with all the buildings thereon, and the privileges and appurtenances thereunto belonging unto the grantee, his heirs and assigns forever, in the manner in which the same is conveyed, or intended so to be by the deed, and according to its true intent.