private @Nullable @Nls String saveLocalChanges(@NotNull Collection<? extends VirtualFile> rootsToSave) {
    try {
      mySaver.saveLocalChanges(rootsToSave);
      return null;
    }
    catch (VcsException e) {
      LOG.warn(e);
      String message = mySaver.getSaveMethod().selectBundleMessage(
        GitBundle.message("rebase.notification.failed.stash.text"),
        GitBundle.message("rebase.notification.failed.shelf.text")
      );
      return new HtmlBuilder().append(message).br().appendRaw(e.getMessage()).toString();
    }
  }
private @Nullable @Nls String saveLocalChanges(@NotNull Collection<? extends VirtualFile> rootsToSave)