These provisions are as follows: "(6). a person who is deemed to have ceased to occupy a building within the meaning of Section 12(2), shall not be allotted that or any other non residential building for a period of two years from the date of such. deemed cessation: Provided that (a) If the District Magistrate is satisfied in a case referred to in Section 12(2) that the admission of partner or new partner is bona fide transaction and not a mere cover for subletting, he shall, if any application had been made in that behalf before the admission of such partner or new partner, allot the non residential ; building in question afresh to the newly constituted or reconstituted firm; X X X 397 Under Rule 19, where an allotment or release of a building or part thereof is ordered under section 16(1) on the ground inter alia of deemed vacancy within the meaning of section 12, no such order is to be executed until after the expiration of fifteen days from the service upon the occupant of a notice to vacate that building or part thereof, as the case may be.