未初始化的常量AFMotion :: HTTP :: AFFormURLParameterEncoding（NameError）

Question

最近afmotion开始上升错误，即使是简单的请求

$ rake
     Build ./build/iPhoneSimulator-6.1-Development
     Build vendor/Pods
  Simulate ./build/iPhoneSimulator-6.1-Development/Network.app
(main)> AFMotion::HTTP.get("http://google.com") do |result|
(main)>     p result.body
(main)> end
2013-05-21 18:29:00.904 Network[75552:11303] http.rb:37:in `parameter_encoding': uninitialized constant AFMotion::HTTP::AFFormURLParameterEncoding (NameError)
  from http.rb:14:in `block in included:'
=> #<NameError: uninitialized constant AFMotion::HTTP::AFFormURLParameterEncoding>

此代码几周前就可以运行了。 有没有人有同样的问题，知道如何解决这个问题？

我的版本设置如下：

ruby version: 2.0.0-p195 (1.9.3-p194 also fails)
rubymotion version: 2.0
afmotion version: 0.4
AFNetworking version: 1.2.1