Slicing Bug that was effecting Nested Tensor (#79445)
While working on nested tensor I was getting aborts thrown while running Pytest. For nested tensors `self_sizes` is initialized with an c10::nullopt. The operator * which gets the value from the optional is not instantiated so it throws via a c++ assert.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/79445
Approved by: https://github.com/soulitzer
