Comment 87 for bug 1569237

Yes, you can "sudo su" from the vagrant user and you'll get root.

You cannot login as root directly (the account is locked in the "passwd -l" sense: there is no password).

The changes are already live in artful (using the "ubuntu/artful64" box for example). I'd like to have some feedback before backporting the changes: it's a relatively large task, I'd like to make sure the changes are good before I start.