Enable undefined at::Tensor to be passed as Output (#16730)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/16730
with Jerry's new updates Tensor must be defined -- as a result I've needed to update the shim for caffe2 ops being used in PyTorch
Reviewed By: smessmer
Differential Revision: D13946950
fbshipit-source-id: 6f77877c61a743f82bdfc2ad04d6ab583000cc18
