def build_rake_in
    gem_ruby = Gem.ruby
    Gem.ruby = @@ruby
    env_rake = ENV["rake"]
    ENV["rake"] = @@rake
    yield @@rake
  ensure
    Gem.ruby = gem_ruby
    if env_rake
      ENV["rake"] = env_rake
    else
      ENV.delete("rake")
    end
  end
#
Allows the proper version of +rake+ to be used for the test.