clipping fails when header has title

[Derek Poon]

> I'm not top posting.

%% An error occurs when making clips when there is a header with a
%% title.  When the title is present, the clips are generated
%% successfully, but the full-score layout fails with:
%%
%%  ERROR: Wrong type (expecting pair): ()

\version "2.10.33"

% Equivalent to invoking lilypond with the -dclip-systems option
#(ly:set-option 'clip-systems #t)

\paper { ragged-right=##t }
\header { title = "Remove title to make clip work" }
\relative { c1 d }
\layout {
  clip-regions = #(list (cons (make-rhythmic-location 1 0 1)
                              (make-rhythmic-location 2 0 1)))
}