openstack-nova in OSP 7 requires the python-oslo-config package, but this fact isn't reflected in the package dependencies.  After upgrading the nova packages from OSP 6 to OSP 7, attempts to run nova-manage db sync fail with:

  File "/usr/bin/nova-manage", line 6, in <module>
    from nova.cmd.manage import main
  File "/usr/lib/python2.7/site-packages/nova/cmd/manage.py", line 64, in <module>
    from oslo_config import cfg
ImportError: No module named oslo_config
Can't determine the existing sync level.
Please ensure the database is running and already initialised.

Affected version:

openstack-nova-common-2015.1.0-16.el7ost.noarch