BugFix: Setting MT model to evaluate mode while training classifier.
BugFix: Setting MT model to evaluate mode while training classifier.

We used to set the model to `training` mode while training the
classifier earlier, which meant that the representations for the
words would be different during train/test time (because of varying
dropout effects)

fdalvi/nmt-repr-analysis,boknilev/nmt-repr-analysis,boknilev/nmt-repr-analysis