All or any portion of the applicable requirements of this Article 14 shall not apply to employees covered by a bona fide collective bargaining agreement if (1) such requirements are expressly waived in the collective bargaining agreement in clear and unambiguous terms, or (2) the agreement was entered into before the effective date of the ordinance enacting this Article 14, on file with the Clerk of the Board of Supervisors in File No. 160065. The exception designated (2) in the preceding sentence shall not apply to any such agreement once it has been extended or has expired.