Where a registered mortgage is discharged, the registrar shall, on the production of the mortgage deed with a receipt for the mortgage money endorsed thereon, duly signed and attested, make an entry in the register book to the effect that the mortgage has been discharged, and on that entry being made the estate, if any, which passed to the mortgagee shall vest in the person in whom (having regard to intervening acts and circumstances, if any) it would have vested, if the mortgage had not been made.