Hm.  I uninstalled the stable version and installed the nightly, but now things appear to be broken further.  The torch module seems to be mostly empty when I inspect it with help('torch'), showing only the submodules nn and utils - no cuda, which means that the second we hit a torch.cuda reference it falls over.
If it helps, I installed torch-nightly via conda install pytorch-nightly cudatoolkit=10.0 -c pytorch , and it installed pytorch/win-64::pytorch-nightly-1.2.0.dev20190714-py3.7_cuda100_cudnn7_0.
Having said that, the nightly that was mentioned as working in that thread is from February.  I’m going to see if I can pull an older version of pytorch (either one of the older nightlies or 1.0.0, which was mentioned to be working in that thread) and see where that takes me.
edit: It’s a hack, but making a call to torch.cuda.current_device() (as mentioned in that thread) appears to resolve this issue.