Notwithstanding the provisions of section nineteen of this article, no payment shall be made to creditors of any one class until all those of the preceding class or classes shall be fully paid; and when the assets are not sufficient to pay all the creditors of any one class, the creditors of such class shall be paid ratably; but a personal representative who, after twelve months from his qualification, pays a debt of his decedent, shall not thereby be personally liable for any debt or demand against the decedent of equal or superior dignity, whether it be of record or not, unless before such payment he shall have notice of such debt or demand by action, suit of presentation thereof to the commissioner of accounts within the time allowed by law.