Ensure there aren't variables in checked_tensor_unwrap, checked_tenso… (#15105)
Summary:
…r_list_unwrap.
These functions use unsafeGetTensorImpl(), which doesn't work with Variables (in a silent way that may blow up later).
So let's do early checking.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/15105
Reviewed By: ezyang
Differential Revision: D13429149
Pulled By: gchanan
fbshipit-source-id: b85f6f5b7cdb9a6dd0c40205b924c840a3920ba0
