Not able to create bootable NFS volume when using multiple cinder backends

Issue

• The Openstack enviroment has multiple cinder backends installed. When trying to create a nfs volume using the following command, it ends up on an RBD host.

    # cinder create --volume-type nfs --image-id $GLANCEIMAGEID --display-name vol${RANDOMKEY} 50 

This results in the following

cinder show 7e172030-45d1-4fa0-afce-b97e488de456 | egrep "name|host-attr|type" 
|          attachments           |                             [{u'device': u'vda', u'server_id': u'91b64d30-ea09-4eec-ada7-a17f90dc187a', u'id': u'7e172030-45d1-4fa0-afce-b97e488de456', u'host_name': None, u'volume_id': u'7e172030-45d1-4fa0-afce-b97e488de456'}]                             |
|          display_name          |                                                                                                                             vol22624                                                                                                                            |
|     os-vol-host-attr:host      |                                                                                                                      example.com@cinder-rbd                                                                                                                     |
| os-vol-mig-status-attr:name_id |                                                                                                                               None                                                                                                                              |
|     volume_image_metadata      | {u'container_format': u'bare', u'min_ram': u'0', u'disk_format': u'raw', u'image_name': u'CEL-6.5-SRV-DEV', u'image_id': u'ada6b3f2-f926-4cfe-b6e5-df7a2c162ea8', u'checksum': u'0de41afb39dc9174cb2e2ad2922845bd', u'min_disk': u'0', u'size': u'42949712384'} |
|          volume_type           |                                                                                                                               nfs                                                                                                                               |