Whenever all or any part of a township has been incorporated as a city and the incorporation of such city has not been completed by the adoption of a charter therefor, then the township board may act hereunder on behalf of both the city and the remainder of the township, either jointly or severally, and for the purposes of this act shall be deemed to be the governing body of such city as well as that of the township. Pending the adoption of such charter, any duty imposed by the provisions of this act upon an officer or governing body of the city, shall be performed by the corresponding officer or governing body of the township, and all papers, documents and notices may be served upon the township clerk. In event of a referendum upon a contract entered into by the township board solely on behalf of such a city, then only the registered electors residing within the city incorporated territory shall be qualified to sign the petition therefor and to vote at the election. The township registration records shall be used unless there shall have been a previous registration of electors in the city. In the event that the city incorporated territory should revert to the township status by reason of the failure to adopt a charter for said city, then any action taken by the township board on behalf of such city shall be binding upon the township.