No laborer whose employment begins after June thirtieth, nineteen hundred and thirty-seven, shall be subject to the provisions of section seventy-seven, seventy-seven D or seventy-eight. Wherever in said section seventy-seven, seventy-seven D or seventy-eight a number of years of service is specified as a requirement of eligibility to receive a pension, such service need not be continuous.
Mass. Gen. Laws ch. 32, § 78A