Fix #3954 - GPT2 is not traceable (#3955)
Fix #3954 - GPT2 is not traceable (#3955)

* Update sqrt computation so it can survive a torch.jit.trace

* Update modeling_gpt2.py

Co-authored-by: Patrick von Platen <3f65d0f67d3758130584b6bd9911c60cc3d4ded4@gmail.com>
huggingface/pytorch-transformers,huggingface/transformers,huggingface/transformers,huggingface/transformers,huggingface/transformers