Comment 4 for bug 1256935

The _xform_security_group function in openstackclient/compute/v2/security_group.py is being called with sgroup set to:

{u'from_port': None, u'group': {u'tenant_id': u'db73ba54c4d04066a4c151be0e4ec5de', u'name': u'default'}, u'ip_protocol': None, u'to_port': None, u'parent_group_id': u'8c49cd42-7c42-4a1f-af1d-492a0687fc12', u'ip_range': {}, u'id': u'674861df-3f94-4d52-91b1-c06932592914'}

The error stems from trying to format the port_range value:

    info.update(
        {'port_range': "%u:%u" % (
            info.pop('from_port'),
            info.pop('to_port'),
        )}
    )

At first glance this seems like a valid rule (it's based on security groups rather than ports), so this should probably require that both from_port and to_port are not None.