I think I did at first (when following again the readme) but I am not sure …
I re-checked dependencies and re-cloned the source.
I will try again from scratch:
git submodule sync
git submodule update --init --recursive
LDFLAGS="-L/usr/local/opt/llvm/lib" CPPFLAGS="-I/usr/local/opt/llvm/include" TORCH_CUDA_ARCH_LIST=6.1 python3 setup.py install