I’ve just tried the same thing as above in multiple configurations (the nightly version did install with CUDA on Ubuntu):

Arch linux, torch 1.2, python 3.8, no CUDA
Ubuntu, torch 1.3, python 3.6, CUDA 10.1
Ubuntu, nightly build, python 3.6, CUDA 10.1

In all cases backward hangs.
It would already be useful to know whether anyone has got this to run.
I have also created an issue on github asking about this: https://github.com/pytorch/pytorch/issues/32045 23