pytorch

0a6ac317 - [PT-D][DDP][BE] Add unit tests for Forward and Backward Hook (#74063)

[PT-D][DDP][BE] Add unit tests for Forward and Backward Hook (#74063) Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/74063 Address the issue https://github.com/pytorch/pytorch/issues/66229 as part of BE effort. Basically: 1. We remove the stale comment which confuses users. 2. Add more unit tests to test the forward/backward hook working for DDP. ghstack-source-id: 151463380 Test Plan: CI Reviewed By: rohan-varma Differential Revision: D34800830 fbshipit-source-id: 21133209323b2b5eda0dd6472f6309d4fb779b97 (cherry picked from commit b9b165c8305572128395daffafc13fcac8b85e29)