Return NotImplemented from tensor arithmetic operators (#26507)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/26333
This effectively rewrites all infix arithmetic operators *op* as:
```python
def __op__(self, other):
try:
return self.op(other)
except TypeError:
return NotImplemented
```
Where `TypeError` is raised from the argument parser when `other` is not a `Tensor`. This should be okay, so long as `TypeError` isn't raised by the function for any other reasons. I couldn't find any examples where this was an issue.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/26507
Differential Revision: D17669097
Pulled By: ezyang
fbshipit-source-id: 2c1a1087057c9298915d713d3fea7d682d014c72
