When any person who has been committed for treason or felony, plainly and specially expressed in the warrant of commitment, upon his prayer in open court to be brought to his trial, shall not be indicted some time in the next term of the superior or criminal court? ensuing such commitment, the judge of the court, upon notice in open court on the last day of the term, shall set at liberty such prisoner upon bail, unless it appear upon oath that the witnesses for the State could not be produced at the same term; and if such prisoner, upon his prayer as aforesaid, shall not be indicted and tried at the second term of the court, he shall be discharged from his imprisonment: Provided, the judge presiding may, in his discretion, refuse to discharge such person if the time between the first and second terms of the court be less than four months. (1868-9, c. 116, s. 33; Code, s. 1658; Rev., s. 3155; 1913, c. 2; C.S., s. 4521.)