(1) Subject to such restrictions, reservations or conditions as may be contained in any warrant issued under section 154 or section 155 and to the provision of sub-section (2), a confirming authority may, when confirming the sentence of a court-martial, mitigate or remit the punishment thereby awarded, or commute that punishment for any punishment or punishments lower in the scale laid down in section 71.
     (2) A sentence of transportation shall not be commuted for a sentence of imprisonment for a term exceeding the term of transportation awarded by the Court.