Disapproval of a plan shall not serve to terminate any rights which shall
have accrued under the provisions of this section, provided an appeal from the
decision disapproving said plan is made under applicable provisions of law.
Such appeal shall stay, pending either (1) the conclusion of voluntary
mediation proceedings and the
filing of a written agreement for judgment or stipulation of dismissal, or
(2) the entry of an order or decree
of a court of final jurisdiction, the applicability to land shown on said plan
of the provisions of any zoning ordinance or by-law which became effective
after the date of submission of the plan first submitted, together with time
required to comply with any such agreement or with the terms of any order or
decree of the court.