Section 15. If appraisers appointed under section thirteen certify that property so seized is perishable and likely to depreciate in value by being kept, any district court may order a sale by auction of such property at such time and after such notice as the order, which shall be endorsed on the inventory, shall direct; but this section shall not affect the power of the court in which the libel is pending to order a sale of the property for sufficient cause at any time during the pendency of the libel.