Notwithstanding any provision of the general statutes or special act 01-1, no municipality or subdivision of a municipality that provides group health insurance benefits to a retiree of the municipality or subdivision as of June 2, 2006, shall diminish or eliminate such retiree’s benefits in violation of any collective bargaining agreement. Nothing in this section shall be construed to prohibit such municipality or subdivision from selecting an alternative insurance carrier to provide such retiree’s benefits as long as the benefits provided by the alternative insurance carrier are at least equivalent to the benefits previously provided by such municipality or subdivision to such retiree, unless such retiree, as of the effective date of such employee’s retirement, is covered by a collective bargaining agreement, negotiated in accordance with the provisions of sections 7-467 to 7-477, inclusive, with a provision specifying that such retiree is entitled to the same health insurance benefits provided to active employees of the municipality as a result of collective bargaining.