Simplify env creation when running Windows tests (#17916)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/13465.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/17916
Differential Revision: D14460589
Pulled By: soumith
fbshipit-source-id: e952d08648b833cfd4a8551355ecd68045fea25c
