If the accused person pleads any plea other than the plea of guilty or a plea to the jurisdiction of the court, he shall be deemed by such plea, and without any further form, to have demanded that the issues raised thereby shall be tried by a jury, and shall be entitled to have them tried accordingly, but if the plea is that the accused person has already been acquitted or convicted, or that he has received the Royal pardon, of the crime charged in the indictment the judge shall determine the plea in such manner and upon such evidence as he thinks fit, and may, in his discretion, order a jury to be empanelled and sworn to try any question of fact necessary for such determination.