Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/20924

I found a python3 bug for deserializing caffe2 code. The exception thrown is Unicode related error instead of just decode error, and we need to catch that as well

Reviewed By: ipiszy

Differential Revision: D15293221

fbshipit-source-id: 29820800d1b4cbe5bf3f5a189fe2023e655d0508