Make sure the right version of the code is loaded. Without this the
rdoc version bundled with ruby is always loaded instead. Reported
upstream but won't be fixed because rubygems has slightly different
behavior.

http://rubyforge.org/tracker/index.php?func=detail&aid=28758&group_id=627&atid=2472


Index: trunk/bin/rdoc
===================================================================
--- trunk/bin/rdoc	(revision 650)
+++ trunk/bin/rdoc	(working copy)
@@ -8,6 +8,7 @@
 #
 #  $Revision: 1.1 $
 
+$:.unshift(File.dirname(__FILE__) + '/../lib') unless $:.include?(File.dirname(__FILE__) + '/../lib')
 require 'rdoc/rdoc'
 
 begin