A mortgage bond, other than a kustingbrief, whether special or general passed for the purpose of securing the payment of a debt not previously secured, which was incurred more than two months prior to the lodging of the bond with the registrar of deeds concerned for registration or for the purpose of securing the payment of a debt incurred in novation of or substitution for any such first-mentioned debt, shall not confer any preference if the estate of the mortgage debtor is sequestrated within a period of six months after such lodging: Provided that a mortgage bond shall be deemed not to have been lodged as aforesaid, if it was withdrawn from registration.