Comment 6 for bug 1354050

Here's the exact error from `neutron-db-manage --config-file /etc/neutron/neutron.conf stamp head` command:

root@node-1:~# neutron-db-manage --config-file /etc/neutron/neutron.conf --config-file /etc/neutron/plugin.ini stamp head
No handlers could be found for logger "neutron.common.legacy"
Traceback (most recent call last):
  File "/usr/bin/neutron-db-manage", line 10, in <module>
    sys.exit(main())
  File "/usr/lib/python2.7/dist-packages/neutron/db/migration/cli.py", line 169, in main
    CONF.command.func(config, CONF.command.name)
  File "/usr/lib/python2.7/dist-packages/neutron/db/migration/cli.py", line 88, in do_stamp
    sql=CONF.command.sql)
  File "/usr/lib/python2.7/dist-packages/neutron/db/migration/cli.py", line 60, in do_alembic_command
    getattr(alembic_command, cmd)(config, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/alembic/command.py", line 257, in stamp
    script.run_env()
  File "/usr/lib/python2.7/dist-packages/alembic/script.py", line 193, in run_env
    util.load_python_file(self.dir, 'env.py')
  File "/usr/lib/python2.7/dist-packages/alembic/util.py", line 177, in load_python_file
    module = load_module(module_id, path)
  File "/usr/lib/python2.7/dist-packages/alembic/compat.py", line 39, in load_module
    return imp.load_source(module_id, path, fp)
  File "/usr/lib/python2.7/dist-packages/neutron/db/migration/alembic_migrations/env.py", line 42, in <module>
    importutils.import_class(class_path)
  File "/usr/lib/python2.7/dist-packages/neutron/openstack/common/importutils.py", line 33, in import_class
    traceback.format_exception(*sys.exc_info())))
ImportError: Class openvswitch cannot be found (['Traceback (most recent call last):\n', ' File "/usr/lib/python2.7/dist-packages/neutron/openstack/common/importutils.py", line 28, in import_class\n __import__(mod_str)\n', 'ValueError: Empty module name\n'])