/tmp/run ownership problem

[PenelopeFudd]

I've encountered a small bug:

$ sudo -u rabbitmq systemctl
.... some output ....

$ sudo -u postgres systemctl

Traceback (most recent call last):
  File "/usr/bin/systemctl", line 6408, in <module>
    systemctl_debug_log = os_path(_root, expand_path(SYSTEMCTL_DEBUG_LOG, not _user_mode))
  File "/usr/bin/systemctl", line 420, in expand_path
    RUN = get_RUN(root)
  File "/usr/bin/systemctl", line 334, in get_RUN
    os.makedirs(path) # "/tmp/run"
  File "/usr/lib/python2.7/os.py", line 157, in makedirs
    mkdir(name, mode)
OSError: [Errno 17] File exists: '/tmp/run'

Looking at the code, it appeared that systemctl should have detected that the user was not "root" and used /tmp/run-$user, but on closer inspection it's actually setting root=True if the --user CLI option isn't set.

Essentially there's confusion about what the root flag means:

• Running with euid=0
• Running systemctl on "system" units (versus "user" units)

Possible solutions:

• Maybe use /tmp/run.{os.geteuid()} ?
• I would have suggested removing /tmp/run after execution completes, but if there's two copies running at the same time, that would break things even more.
• Use tempfile.TemporaryDirectory ?
• Perhaps /tmp/run.{os.getpid()} and remove it after?

Thanks for taking the time to write this package, it's really helpful!