private static @Nullable String readRebaseDirBranchFile(@NonNls File rebaseDir) {
    if (rebaseDir.exists()) {
      File headName = new File(rebaseDir, "head-name");
      if (headName.exists()) {
        return DvcsUtil.tryLoadFileOrReturn(headName, null, CharsetToolkit.UTF8);
      }
    }
    return null;
  }
private static @Nullable String readRebaseDirBranchFile(@NonNls File rebaseDir)