beego: fix #702 auto render

@@ -720,12 +720,11 @@ func (p *ControllerRegistor) ServeHTTP(rw http.ResponseWriter, r *http.Request)
 				}
 
 				//render template
-				if !w.started {
+				if !w.started && context.Output.Status == 0 {
 					if AutoRender {
 						if err := execController.Render(); err != nil {
 							panic(err)
 						}
-
 					}
 				}
 			}