In any county having a charter providing for a civil service system for county employees, the board of supervisors may require any person included within the civil service system to give an official bond in an amount to be prescribed by the board. He may be included with other persons in a schedule bond executed by a qualified corporate surety and inuring to the benefit of the county and of the officer under whom he holds office or employment. The liability of the surety on the schedule bond is not affected by any change of the person holding any principal office or in the membership of any board or commission, but continues as long as any person named in the schedule bond is included therein and continues to exercise the duties of his office or employment.