Upon the consolidation of two or more cities, or the annexation of any city to another city, as provided in this chapter, the title to all property and assets owned by, or held in trust for, such former city shall vest in such consolidated city, or annexing city, as the case may be: PROVIDED, That if any such former city, shall be indebted, the proceeds of the sale of any such property and assets not required for the use of such consolidated city, or annexing city, shall be applied to the payment of such indebtedness, if any exist at the time of such sale.