Rails 3.0.0.beta4 metal absent

Rails 3.0.0.beta4 prevents from execution of Metal parts of Rails application, however 3.0.0.beta3 works very well.

# Allow the metal piece to run in isolation
require File.expand_path('../../../config/environment',  __FILE__) unless defined?(Rails)

class TestBug < Sinatra::Application
  include JetSpade::Accessor

  get '/bug' do
    content_type :text
    status 200
    'oh no not you again'
  end
end

How to reproduce

• Take a Rails app
• Add any Metal part
• Try to access the metal-handled URL
• Enjoy the Routing Error