in respect of any proceeding under this Act an income-tax authority ceases to
exercise jurisdiction and is succeeded by another who has and exercises
jurisdiction, the income-tax authority so succeeding may continue the
proceeding from the stage at which the proceeding was left by his predecessor :
Provided that the assessee concerned may
demand that before the proceeding is so continued the previous proceeding or
any part thereof be reopened or that before any order
of assessment is passed against him, he be reheard.