No assignment or transfer of a contract authorized or provided for in this Article, or of any rights thereunder, shall operate to relieve the surety or sureties on any bond executed in connection with such contract, as herein provided for, from the obligations or liabilities assumed in and by such bond, nor change or in any manner or degree qualify such obligations or liabilities. All such assignments or transfers of contracts must be recorded in the County Recorder's office and due notice thereof given to the Director of Public Works.