Red Hat Enterprise Linux OpenStack Platform upgrade from 3.0 to 4.0 has failed with error 'ImportError: No module named services.agent_loadbalancer.plugin'

Issue

• While upgrading a system from OpenStack 3.0 (Grizzly) to 4.0 (Havana), it's failed with a error 'finding module failed'.

$ neutron-db-manage --config-file /etc/neutron/neutron.conf --config-file /etc/neutron/plugin.ini current
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/python2.6/site-packages/neutron/db/migration/cli.py", line 143, in main
    CONF.command.func(config, CONF.command.name)
  File "/usr/lib/python2.6/site-packages/neutron/db/migration/cli.py", line 59, in do_alembic_command
    getattr(alembic_command, cmd)(config, *args, **kwargs)
  File "/usr/lib/python2.6/site-packages/alembic/command.py", line 189, in current
    script.run_env()
  File "/usr/lib/python2.6/site-packages/alembic/script.py", line 191, in run_env
    util.load_python_file(self.dir, 'env.py')
  File "/usr/lib/python2.6/site-packages/alembic/util.py", line 186, in load_python_file
    module = imp.load_source(module_id, path, open(path, 'rb'))
  File "/usr/lib/python2.6/site-packages/neutron/db/migration/alembic_migrations/env.py", line 44, in <module>
    importutils.import_class(class_path)
  File "/usr/lib/python2.6/site-packages/neutron/openstack/common/importutils.py", line 30, in import_class
    __import__(mod_str)
ImportError: No module named services.agent_loadbalancer.plugin