anchor.diff:    }
   
     Future clearRemoteRefs() {
  -    return root.getDirectory(GIT_REFS_REMOTES_ORIGIN_PATH).then(
  +    return root.createDirectory(GIT_REFS_REMOTES_ORIGIN_PATH).then(
           (dir) => dir.removeRecursively()).catchError((e){});
     }
   
  
positive.code:     });
    }
  
    Future _init() {
      return FileOps.createDirectoryRecursive(_rootDir,
          gitPath + OBJECT_FOLDER_PATH).then((chrome.DirectoryEntry objectDir) {
        this.objectDir = objectDir;
        return FileOps.createFileWithContent(_rootDir, gitPath + HEAD_PATH,
            GIT_HEAD_FILE_DEFAULT_CONTENT, 'Text').then((entry)  {
              return _initHelper();
            }, onError: (e) {
              print(e);
              throw e;
            });
      }, onError: (e) {
        throw e;
      });
  
negative.code:   }
  
    Future<List<String>> getRemoteHeads() {
      return _rootDir.createDirectory(GIT_REFS_REMOTES_ORIGIN_PATH).then((dir) {
        return FileOps.listFiles(dir).then((List<chrome.Entry> entries) {
          return entries.map((entry) => entry.name).toList();
        });
  