Fix LambdaLR scheduler side effects (#32848)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/32756
Pull Request resolved: https://github.com/pytorch/pytorch/pull/32848
Differential Revision: D19859736
Pulled By: vincentqb
fbshipit-source-id: 43b3cbb2b6bed208c75aad37aebc2a8a9565fe0d
