FileSystemManager.rename()bug

-执行到这  任何提示也没有。。。。 代码如下：

//下载文件

        downfile: function () {

                const manage = wx.getFileSystemManager();

                wx.downloadFile({

                        url: "http://www.zzs5.com/uploadfile/2017/0320/20170320122300245.rar",

                        success: function (res) {

                                console.log(res);

                                var savePath = "${ wx.env.USER_DATA_PATH }/save/";

                                manage.rename({

                                        oldPath: res.tempFilePath,

                                        newPath: savePath,

                                        success: function (res) {

                                                console.log(res.tempFilePath);

                                        }

                                });

                        }

                });

        },

console最后的提示是 console.log(res);的信息。 就啥都没了。temp 文件夹下有下载的文件， log记录这是最后一条 2019-3-19 11:5:46 [log] wx.downloadFile success callback with msg downloadFile:ok 这是咋回事？？