Cloned DCB authentication data was freed twice

This caused all Tee filter sessions to crash when the branch DCB was closed.

server/core/dcb.c

@@ -369,9 +369,17 @@ dcb_final_free(DCB *dcb)
         if (SESSION_STATE_DUMMY != local_session->state)
         {
             session_free(local_session);
+
+            if (local_session->client_dcb == dcb)
+            {
+                /** The client DCB is freed once all other DCBs that the session
+                 * uses have been freed. This will guarantee that the authentication
+                 * data will be usable for all DCBs even if the client DCB has already
+                 * been closed. */
                 return;
             }
         }
+    }
     dcb_free_all_memory(dcb);
 }
 

server/core/session.c

@@ -426,8 +426,11 @@ session_free(SESSION *session)
      *
      */
     if (session->client_dcb)
+    {
+        if (!DCB_IS_CLONE(session->client_dcb))
         {
             mysql_auth_free_client_data(session->client_dcb);
+        }
         dcb_free_all_memory(session->client_dcb);
     }
     /**