Correctly zero padding index in TransformerSentenceEncoder
Correctly zero padding index in TransformerSentenceEncoder

Summary: Pull Request resolved: https://github.com/pytorch/fairseq/pull/912

Differential Revision: D16536561

Pulled By: myleott

fbshipit-source-id: 54c5c20a826a14f4e690770e027bcb282acdf911

pytorch/fairseq,pytorch/fairseq,pytorch/fairseq