If the City Council shall have rejected any initiative bill, or shall, within 30 days after receipt thereof, have failed to take final action thereon, or shall have passed a different bill dealing with the same subject, the said rejected initiative bill and such different bill dealing with the same subject, if any has been passed, shall be submitted by the Finance Director to the qualified electors for approval or rejection at the next municipal general election: Provided; That the City Council may, in its discretion, provide for a special election at which the vote shall be taken.