Fix for user kicked off after login on some hosts

Docker-DCO-1.1-Signed-off-by: SvenDowideit <SvenDowideit@home.org.au> (github: SvenDowideit)

I didn't need it for my boot2docker, but a debian test system confirmed the need

from https://groups.google.com/forum/#!topic/docker-user/NsCZMrUf-k0