Section 15. Effect of loss of right of pre-emption prior to decree

No decree for pre-emption shall be passed in favour of any person unless he has a subsisting right of pre-emption at the time of the decree, but where a decree for pre-emption has been passed in favour of a plaintiff, whether by a court of the first instance or of appeal, the right of such plaintiff shall not be affected by any transfer or loss of his interest occurring after the date of such decree: Provided that no voluntary transfer made in favour of the purchaser after the institution of a suit for pre-emption shall defeat any right which the plaintiff had at the date such institution.