(6)The period during which a person is absent from prison in pursuance of a parole order in force shall be reckoned as a part of the period of imprisonment to which he was sentenced:Provided that if the parole order is revoked under sub-section (4) for failure on the part of the person released on parole to observe any of the conditions of parole, the period of such absence shall not be so reckoned, and the person shall have to serve the whole of the unexpired term of his original sentence of imprisonment.
