Two amendments for the shape analysis (#18271)
Summary:
Two small refinements to the shape analysis:
- `detach` can set requires grad to false for dimensioned tensors (not sure if I would also need to deal with Complete?).
- add `batch_norm_stats`.
I noticed these while looking at what's going on when trying to code batch norm manually. (Hi wanchaol )
Pull Request resolved: https://github.com/pytorch/pytorch/pull/18271
Differential Revision: D14561303
Pulled By: ezyang
fbshipit-source-id: 64a6879392e77403c44f2ed82f84b6397754d0ea
