Mention issue number in the JIT workaround comments (#20222)
Summary:
This just updates the `JIT` comments with the issue number #20215. Hopefully this will stop the proliferation of the workaround. :)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/20222
Differential Revision: D15259007
Pulled By: ezyang
fbshipit-source-id: 5060a351aa618c6dae49d0b7a6ac9b0f57f2490a
