§ Where the tenant of any holding charged with the repayment of any moneys expended or to be expended by the Land Commission or the Congested Districts Board in erecting or improving buildings on the holding enters into an agreement with the Commission or the Board for the purchase of the holding under the Land Purchase Acts, he shall not by reason of anything contained in Section thirty-five of the Act of 1896 be discharged from liability in respect of that charge.