Comment 0 for bug 1681073

Env: devstack master branch

Steps to reproduce:
1. Go to admin/volume types panel
2. Create volume type with any name
3. Go to project/Consistency Groups panel
4. Create Consistency Group and add the volume type we just created
5. Submit Create Consistency Group form

it will throws an exception.

Exception info:
Internal Server Error: /project/cgroups/create/
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/django/core/handlers/base.py", line 132, in get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/opt/stack/horizon/horizon/decorators.py", line 36, in dec
    return view_func(request, *args, **kwargs)
  File "/opt/stack/horizon/horizon/decorators.py", line 52, in dec
    return view_func(request, *args, **kwargs)
  File "/opt/stack/horizon/horizon/decorators.py", line 36, in dec
    return view_func(request, *args, **kwargs)
  File "/opt/stack/horizon/horizon/decorators.py", line 84, in dec
    return view_func(request, *args, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/django/views/generic/base.py", line 71, in view
    return self.dispatch(request, *args, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/django/views/generic/base.py", line 89, in dispatch
    return handler(request, *args, **kwargs)
  File "/opt/stack/horizon/horizon/workflows/views.py", line 199, in post
    exceptions.handle(request)
  File "/opt/stack/horizon/horizon/exceptions.py", line 352, in handle
    six.reraise(exc_type, exc_value, exc_traceback)
  File "/opt/stack/horizon/horizon/workflows/views.py", line 194, in post
    success = workflow.finalize()
  File "/opt/stack/horizon/horizon/workflows/base.py", line 824, in finalize
    if not self.handle(self.request, self.context):
  File "/opt/stack/horizon/openstack_dashboard/dashboards/project/cgroups/workflows.py", line 323, in handle
    vol_type.extra_specs['volume_backend_name']
KeyError: 'volume_backend_name'