count down latch if we don't have any changes in cluster update settings

src/main/java/org/elasticsearch/action/admin/cluster/settings/TransportClusterUpdateSettingsAction.java

@@ -109,6 +109,7 @@ public class TransportClusterUpdateSettingsAction extends TransportMasterNodeOpe
                     }
 
                     if (!changed) {
+                        latch.countDown();
                         return currentState;
                     }