Comment 7 for bug 1090592

This change broke running unit tests for me. 822 tests fail with an error similar to this:

Traceback (most recent call last):
  File "/home/johannes/openstack/nova/trunk/nova/tests/test_service.py", line 172, in test_init_and_start_hooks
    serv.start()
  File "/home/johannes/openstack/nova/trunk/nova/service.py", line 425, in start
    verstr = version.version_string_with_package()
  File "/home/johannes/openstack/nova/trunk/nova/version.py", line 87, in version_string_with_package
    return version_info.version_string()
  File "/home/johannes/openstack/nova/trunk/nova/openstack/common/version.py", line 63, in version_string
    for part in self.release_string().split('.'):
AttributeError: 'NoneType' object has no attribute 'split'