Notwithstanding the provisions of any general or special act or municipal ordinance, when an application, petition or request for approval of a subdivision plan for residential property has been filed with or submitted or made to the planning commission of any town, city or borough, or to any other body exercising the powers of such commission, accompanied by a subdivision plan and such other documents as may be required by the regulations of such commission or body, in form and content as to all essential matters as is specified in such regulations, or when any modification of such plan or other documents has been subsequently filed or submitted in connection with the same application, petition or request, which modification is in conformance with such regulations as of the time of filing of the original application, petition or request, neither such original application, petition or request nor such subsequent modification shall be required to comply with, nor shall it be disapproved for the reason that it does not comply with, any change in the subdivision regulations or the boundaries of zoning districts of such town, city or borough taking effect after the filing, submission or making of such original application, petition or request. If such subdivision plan or modification thereof is given final approval, any change in the subdivision regulations made between the time of filing, submitting or making of such application, petition or request and the time of such final approval shall, as to such plan or modification thereof and the land shown thereon, be deemed to take effect following such final approval.