Notwithstanding Section 87419, and notwithstanding provisions of the charter of any city or city and county to the contrary, on and after July 1, 1978, the academic employees of any community college district governed by the charter who serve as the head of a department of the district or in an administrative or supervisory position shall neither acquire nor retain permanent status in that position unless the employee is or becomes eligible for permanent status in accordance with provisions of this code.