Remove duplicate error info

when delete a standard resource class, we can meet with error:
Unable to delete resource class VCPU: Unable to delete resource class VCPU
which is duplicate.

Trivial Fix

Change-Id: Ib5a4bbb75affbb44eb28719b135a73903ce1a3de

nova/api/openstack/placement/handlers/resource_class.py

@@ -111,12 +111,10 @@ def delete_resource_class(req):
         rc.destroy()
     except exception.ResourceClassCannotDeleteStandard as exc:
         raise webob.exc.HTTPBadRequest(
-            _('Cannot delete standard resource class %(rp_name)s: %(error)s') %
-            {'rp_name': name, 'error': exc})
+            _('Error in delete resource class: %(error)s') % {'error': exc})
     except exception.ResourceClassInUse as exc:
         raise webob.exc.HTTPConflict(
-            _('Unable to delete resource class %(rp_name)s: %(error)s') %
-            {'rp_name': name, 'error': exc})
+            _('Error in delete resource class: %(error)s') % {'error': exc})
     req.response.status = 204
     req.response.content_type = None
     return req.response

nova/tests/functional/api/openstack/placement/gabbits/resource-class-in-use.yaml

@@ -55,7 +55,7 @@ tests:
   DELETE: /resource_classes/CUSTOM_GOLD
   status: 409
   response_strings:
-      - Unable to delete resource class
+      - Error in delete resource class
       - Class is in use in inventory
 
 - name: delete the allocation
@@ -66,7 +66,7 @@ tests:
   DELETE: /resource_classes/CUSTOM_GOLD
   status: 409
   response_strings:
-      - Unable to delete resource class
+      - Error in delete resource class
       - Class is in use in inventory
 
 - name: delete the inventory
@@ -75,4 +75,4 @@ tests:
 
 - name: delete resource class
   DELETE: /resource_classes/CUSTOM_GOLD
-  status: 204
+  status: 204