Description of problem:
The deletion of a snapshot fails with the error 

2015-08-18 11:11:39.198 4418 ERROR cinder.volume.manager [req-e721e329-ba76-4088-bce6-dbfb0757fe05 b7bc6cb74f5d4935b8a994d4c4582de2 e577bce6013b4fde98e5e44bc82e7ca1 - - -] Cannot delete snapshot 0b33c534-7f52-4aa5-9fbb-725eb929b771: snapshot is busy

while exists a volume that was created from it. 

Version-Release number of selected component (if applicable):
python-cinder-2015.1.0-3.el7ost.noarch
ceph-common-0.80.8-7.el7cp.x86_64
openstack-cinder-2015.1.0-3.el7ost.noarch
python-cinderclient-1.2.1-1.el7ost.noarch


How reproducible:
100% 

Steps to Reproduce:
1. Create a volume 
2. Take a snapshot of the volume
3. Create a new volume from the snapshot
4. Delete the snapshot 
5. Check the snapshot list

Actual results:
The snapshot stays in a available state

Expected results:
The Cinder client will provide an output that explains why the action failed or set the snapshot with a deleted tag in the Ceph pool and delete the snapshot record in Cinder