Rubinius error

gistfile1.txt

→ ruby -d -W2 --vv test.rb
rubinius 1.2.4dev (1.8.7 77994afa yyyy-mm-dd) [x86_64-apple-darwin10.7.0]
Options:
  Interpreter type: static
  JIT disabled

An exception occurred running test.rb
    Tried to use object of type PackedObject (45) as type LookupTable (35) (TypeError)

Backtrace:
  { } in Builder(Class)#initialize at test.rb:5
         Module(Class)#module_eval at kernel/common/eval.rb:199
          Module(Class)#initialize at kernel/common/module.rb:33
                  Class#initialize at kernel/common/class.rb:58
                         Class#new at kernel/alpha.rb:94
                Builder#initialize at test.rb:5
                 Object#__script__ at test.rb:9
  Rubinius::CodeLoader#load_script at kernel/delta/codeloader.rb:65
  Rubinius::CodeLoader.load_script at kernel/delta/codeloader.rb:90
           Rubinius::Loader#script at kernel/loader.rb:580
             Rubinius::Loader#main at kernel/loader.rb:715

test.rb

class Builder
  def initialize
    @constants = {}
    constants = @constants
    Class.new(Object) do
      define_method :initialize do
        @constants = constants
      end
    end
  end
end

Builder.new