Any defendant against whom a decree or judgment shall be rendered for land, when no assessment of damages has been made under Article 14 (§ 8.01-131 et seq.) of this chapter, may, at any time before the execution of the decree or judgment, present a pleading to the court rendering such decree or judgment, stating that he, or those under whom he claims while holding the premises under a title believed by him or them to have been good, have made permanent improvements thereon, and moving that he should have an allowance for the same which are over and above the value of the use and occupation of such land; and thereupon the court may, if satisfied of the probable truth of the allegation, suspend the execution of the judgment or decree, and impanel a jury to assess the damages of the plaintiff, and the allowances to the defendant for such improvements.