Period of release to be reckoned as imprisonment for commuting period of sentence served.

l

The period during which a person is absent from prison under the provisions of this Act on a license which is in force shall be reckoned as a part of the period of imprison_ ment to which he was sentenced, for the purpose of computing the period of his sentence and for the purpose of computing the amount of remission of his sentence which might be awarded to him under any rules in force reinting to such remissions.