(A) Any municipal corporation may, by a two-thirds vote of its legislative authority, waive, suspend, or alter any of the provisions of this chapter as they apply to that municipal corporation if such waiver, suspension, or alteration is necessary for the municipal corporation to comply with any federal law or any rules adopted pursuant to federal law concerning discrimination in employment.
(B) Any municipal corporation that has adopted the provisions of this chapter as part of its charter may, by a two-thirds vote of its legislative authority, waive, suspend, or alter any of the provisions of this chapter so adopted if such waiver, suspension, or alteration is necessary for the municipal corporation to comply with any federal law or any rules adopted pursuant to federal law concerning discrimination in employment.
(C) A municipal corporation may not under this section make any waiver, suspension, or alteration of provisions of this chapter that relate to matters of promotions within the municipal civil service.