private static @Nullable GitRevisionNumber resolveHead(@NotNull Project project, @NotNull VirtualFile root) {
    try {
      return GitRevisionNumber.resolve(project, root, "HEAD");
    }
    catch (VcsException e) {
      LOG.warn("Couldn't resolve the HEAD in " + root, e);
      return null;
    }
  }
private static @Nullable GitRevisionNumber resolveHead(@NotNull Project project, @NotNull VirtualFile root)