Whenever, subsequent to the date when a conditional apportionment is made to a district and before the conditional apportionment becomes final the boundaries of the district are changed so that the territory of the district is reduced by not to exceed 1 percent of the assessed valuation of the district, as determined by the last equalized assessment roll immediately preceding the effective date of the change of boundaries, and the superintendent of schools of the county having jurisdiction over the district has failed to file the certificate required by Section 15795, showing the change of boundaries, and prior to April 15, 1952, the board has certified to the Controller that the apportionment made to the district has become final, the final apportionment is hereby confirmed, ratified, and validated, and any expenditure of money from the Public School Building Loan Fund according to the terms of the final apportionment is hereby confirmed, ratified, and validated.