In the new guix `guix environment --container` is borken. The reason lies in the 8bc5ca5160db3d82bd5b6b2b7ed80c96f42bd33e of the master branch:
It checks if the file exists and then returns a boolean None of my 3 Guix System machines have this file but they can still run unprivileged containers. Please fix it, thanks very much luhux
