Updated psutil breaking VM provisioning

[Max Brustkern]

On wily I'm getting this right now:
max@eden:~$ sudo su - utah -c '/usr/bin/run_utah_tests.py lp:ubuntu-test-cases/desktop/runlists/default.run -i /home/max/iso/ubuntu/wily-desktop-amd64.iso'
Unhandled error in UTAH:
Traceback (most recent call last):
  File "/usr/bin/run_utah_tests.py", line 128, in <module>
    exitstatus = timeout(config.jobtimeout, run_utah_tests)
  File "/usr/lib/python2.7/dist-packages/utah/timeout.py", line 65, in timeout
    return command(*args, **kw)
  File "/usr/bin/run_utah_tests.py", line 117, in run_utah_tests
    exitstatus, locallogs = run_tests(args, _get_machine(args))
  File "/usr/bin/run_utah_tests.py", line 92, in _get_machine
    return _get_unprovisioned_machine(args, image)
  File "/usr/bin/run_utah_tests.py", line 81, in _get_unprovisioned_machine
    return get_vm(**kw)
  File "/usr/lib/python2.7/dist-packages/utah/provisioning/vm.py", line 632, in get_vm
    return inventory.request(**kw)
  File "/usr/lib/python2.7/dist-packages/utah/provisioning/vm.py", line 606, in request
    return machinetype(machineid=machineid, *args, **kw)
  File "/usr/lib/python2.7/dist-packages/utah/provisioning/vm.py", line 155, in __init__
    if process_checker.check_cmdline(cmdline):
  File "/usr/lib/python2.7/dist-packages/utah/process.py", line 87, in check_cmdline
    cmdlines.append(' '.join(psutil.Process(pid).cmdline))
TypeError: can only join an iterable

I'm looking into a fix.