Bug#781604: `journalctl /dev/sda` shows empty log

[Chris Bainbridge]

>
> Are you running the command as root?

Yes. The error if you run journalctl as a regular user is different:
"No journal files were found." Whereas this just shows an empty log.

This will potentially break any scripts or monitoring tools that query
device information using this format, and people will expect
`journalctl /dev/...` to work since it is the basic method of querying
device logs in systemd.