externals argumental are now taking precedence over the result of

moduleMerge because we may need to alter the result of the configuration
before using it inside other options.

svn path=/nixpkgs/trunk/; revision=17477

pkgs/lib/modules.nix

@@ -280,7 +280,7 @@ rec {
       let module = { inherit (result) options config; }; in
 
       moduleMerge "" (
-        moduleClosure initModules (args // module)
+        moduleClosure initModules (module // args)
       )
     );