deepCopy also copies type information of lists (#23271)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/23271
ghstack-source-id: 87088503
Differential Revision: D16449220
fbshipit-source-id: 551b7cef8f6d0d2d5a56b24ddbe2e0bb2c0c3dbe
