The code looks good to me. The package building was tested by Neel and we found that the venv was built with Python 3+ but the runtime was built against Python 2.7.
As per Dave, Neel may have not used a venv of the correct version as it is working fine on Dav'e system. So, we can commit the patch.
Yeah, that's not ideal, but the same problem exists today. I need to spend some time figuring out how to make that more robust.