Notwithstanding any contract to the contrary or any provision of a record-of-rights, an occupancy-tenant shall not be ejected from his holding by his landlord as such except,--
         (a) as hereinafter provided, for arrears of rent; or
         (b) in execution of a decree of a Civil Court passed on the ground of his having diverted the land to non-agricultural purposes or being chargeable with some other act or omission which, by custom not inconsistent with this Act or with any other enactment for the time being in force, renders him liable to be ejected.