Notwithstanding any other provision of law, whenever the rights of a member of the Public Employees’ Retirement System, the State Teachers’ Retirement System, or a retirement system established under the County Employees Retirement Law of 1937, because of membership in another retirement system, are conditional upon employment within a specified period of time after termination of service in another retirement system, that specified period shall be the period of service in full-time elective office on and after November 6, 1990, if the member was a full-time elective officer on or after that date and becomes a member of any of those retirement systems within 120 days after termination of the full-time elective office.