ZF-7676: backport r17803 to trunk

git-svn-id: http://framework.zend.com/svn/framework/standard/trunk@17804 44c647ce-9c0f-0410-b52a-842ac1e357ba

library/Zend/XmlRpc/Server/System.php

@@ -137,7 +137,9 @@ class Zend_XmlRpc_Server_System
                     $request->setMethod($method['methodName']);
                     $request->setParams($method['params']);
                     $response = $this->_server->handle($request);
-                    if ($response->isFault()) {
+                    if ($response instanceof Zend_XmlRpc_Fault 
+                        || $response->isFault()
+                    ) {
                         $fault = $response;
                     } else {
                         $responses[] = $response->getReturnValue();