fix non-deterministic decoding with exponential smoothing
fix non-deterministic decoding with exponential smoothing

rsennrich/nematus,EdinburghNLP/nematus,rsennrich/nematus,EdinburghNLP/nematus,EdinburghNLP/nematus,rsennrich/nematus,rsennrich/nematus,EdinburghNLP/nematus,rsennrich/nematus,EdinburghNLP/nematus,EdinburghNLP/nematus,rsennrich/nematus