error instead of crashing on attempt to subclass typed tensors (#20283)
Summary:
https://github.com/pytorch/pytorch/issues/20052
typed tensors (e.g. torch.FloatTensor) can't be subclassed. Was causing
crashes and other errors.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/20283
Differential Revision: D15278138
Pulled By: nairbv
fbshipit-source-id: 8493eac4d34dfb76b054362bf0acec02146cd0e2
