7-12-4250. Obligations of municipalities to bondholders. All agreements, conditions, covenants, or restrictions in the ordinance creating the supplemental revolving fund, in the resolution determining that the improvement is of a character for which bonds may be issued under 7-12-4241 through 7-12-4258, and in the resolution authorizing the issuance of bonds shall be binding upon the city or town and may not be thereafter altered or amended to the detriment of the rights of any bondholder so long as any of such bonds are outstanding.