Fix missing deprecation warning for Tensor.nonzero(). (#40187)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/40187
There were two issues:
1) The hand-written definition included an ambiguous default, which made the deprecated signature not selected. This didn't match the handwritten torch.nonzero, now they do.
2) A parsing bug for empty argument lists meant the signature wasn't being marked as deprecated.
Test Plan: Imported from OSS
Differential Revision: D22118236
Pulled By: gchanan
fbshipit-source-id: a433ce9069fef28aea97cbd76f2adf5a285abd73
