In any suit or proceeding in which a county, district, school district or municipal corporation is a party, no person is incompetent as a juror because such person is an inhabitant or taxpayer of the county, district, school district or municipal corporation. In any case where a municipal corporation is a party, the court, upon motion of either party to the suit, made either on the first day of the term of the court or at any other time not less than five days before the day set for the trial, may, in its discretion, disqualify jurors who are citizens or taxpayers of such municipal corporations. But this provision does not apply in any case between a municipal corporation and any citizen or taxpayer of such corporation.