1449. The seller cannot have possession of the thing sold, upon the avoidance of the sale by reason of non-payment of the price, until he or she has repaid to the buyer such part of the price as he or she has received, with the costs of all necessary repairs, and of such improvements as have increased the value of the purchase, to the amount of such increased value. If these improvements be of a nature to be removed, he or she has the option of permitting the buyer to remove them.