3. There is a workaround the fastai.launch, that is probably similar to this one:

I think you can do the launching "manually", something like:
https://github.com/allegroai/clearml/blob/fd2d6c6f5d46cad3e406e88eeb4d805455b5b3d8/examples/frameworks/pytorch/pytorch_distributed_example.py#L160
At least until we understand how to fix it automatically