Whenever the jury list of any county is destroyed by fire or other casualty or it is held by any court of competent jurisdiction that the jury list has been unlawfully prepared or is irregular or illegal, so as to render void the drawing of jurors therefrom, the jury commissioners shall prepare a special jury list for the county immediately in the manner herein prescribed from which special list grand and petit jurors are drawn for the courts of general sessions and common pleas for the county until the annual jury list has been prepared for the county as provided.