RDoc doesn't make a link for a included module

I found another link problem.

% cat t.rb 
class C
  module MMM end
  module M1 end
  module M1::M2
    include MMM
  end
end
% rdoc -q t.rb 
% w3m -dump doc/classes/C/M1/M2.html
C::M1::M2 ^(Module)

In: t.rb 

Included Modules

MMM

[Validate]

% grep -i '<a' doc/classes/C/M1/M2.html
                <a href="../../../files/t_rb.html">
  <p><small><a href="http://validator.w3.org/check/referer">[Validate]</a></small></p>

In above example, MMM in the "Included Modules" is not linked.
I think it should be a link to doc/classes/C/MMM.html.
-- 
Tanaka Akira