[Easy][c10d][DDP] (Reland) Minor fixes (#73569)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/73569
Reland https://github.com/pytorch/pytorch/pull/73299 and https://github.com/pytorch/pytorch/pull/73318 together.
Test Plan: Imported from OSS
Reviewed By: zhaojuanmao
Differential Revision: D34552418
Pulled By: awgu
fbshipit-source-id: 95088d2c1c67cd4fb9bbb115e15ba6b26ae06bdb
(cherry picked from commit 695ebc3dc0ccb08a167445588c293b3a6c3c00b7)
