Whenever it is necessary to hold a special election to fill an unexpired term of an elective office of any city, town, or district, the special election must be held in concert with the next general election that is to be held by the respective city, town, or district concerned for the purpose of electing officers to full terms. This section does not apply to any city of the first class whose charter provision relating to elections to fill unexpired terms are inconsistent with this section.