bug#22565: Cannot talk to upowerd over D-Bus

[Ricardo Wurmus]

I’m trying to figure out why we cannot use the Xfce menu to shut down or
reboot, and while doing that I found that

    loginctl poweroff

(as root on the TTY) does have the intended effect.  When run as a user
I see a similar error as mentioned above:

    Failed to power off: Interactive authentication required.

I think this is just fine.