RDoc: parent class link problem.

I found that RDoc doesn't make a link for a parent class in following
case.

% cat t.rb
module M1
  class C1
  end
  module M2
    class C2 < C1
    end
  end
end
% rdoc -q t.rb
% lynx -dump doc/classes/M1/M2/C2.html

M1::M2::C2 ^(Class)

   In:     [1]t.rb 
   Parent: C1

   [2][Validate]

References

   1. file://localhost/tmp/a/doc/files/t_rb.html
   2. http://validator.w3.org/check/referer

"C1" should be a link to doc/classes/M1/C1.html.
-- 
Tanaka Akira