pytorch

5b9fced7 - add output_process_fn_grad before sum().backward() (#59971)

add output_process_fn_grad before sum().backward() (#59971) Summary: This should fix `to_sparse` test issue. Pull Request resolved: https://github.com/pytorch/pytorch/pull/59971 Test Plan: CI Also: directly examine the RuntimeError thrown from test_unsupported_backward - Before: ``` NotImplementedError: Could not run 'aten::sum' with arguments from the 'SparseCPU' backend. ``` - After: ``` to_dense() not supported for float16 on CPU ``` Reviewed By: soulitzer Differential Revision: D29112558 Pulled By: walterddr fbshipit-source-id: c2acd22cd18d5b34d25209b8415feb3ba28fa104