run_tests.sh -V fails to run tests

I'd like to set up a local Hudson server that will run the suite of nova tests on a branch of OpenStack. My plan was to have it to just run the run_tests.sh script. However, when I try to run the script on the code in the nova trunk, I get the following output:

$ ./run_tests.sh -V
not found.
Installing virtualenv via easy_install... done.
done.
Creating venv...
Traceback (most recent call last):
  File "tools/install_venv.py", line 136, in <module>
    main(sys.argv)
  File "tools/install_venv.py", line 131, in main
    create_virtualenv()
  File "tools/install_venv.py", line 81, in create_virtualenv
    run_command(['virtualenv', '-q', '--no-site-packages', VENV])
  File "tools/install_venv.py", line 50, in run_command
    proc = subprocess.Popen(cmd, cwd=ROOT, stdout=stdout)
  File "/usr/lib/python2.6/subprocess.py", line 633, in __init__
    errread, errwrite)
  File "/usr/lib/python2.6/subprocess.py", line 1139, in _execute_child
    raise child_exception
OSError: [Errno 2] No such file or directory
tools/with_venv.sh: line 4: tools/../.nova-venv/bin/activate: No such file or directory

Is there something I should be doing first? For example, Does OpenStack need to be installed to run these tests?

I'm running on Ubuntu 10.04, not as root.