A bug in rails? About model inherited

My env: ruby-1.9.2-preview3; rails-3.0.0.beta3

class PostFather < ActiveRecord::Base
  def self.inherited(subclass)
  end
end

class Post < PostFather
end

In the console:

> Post.new # => TypeError: can't dup NilClass
> Post.all # => TypeError: can't dup NilClass
> Post.scoped # => TypeError: can't dup NilClass

You can try it yourself;

ActiveRecord is using the inherited method, you need to call super so the ActiveRecord stuff still runs:

class PostFather < ActiveRecord::Base
  def self.inherited(subclass)
    super(subclass)
  end
end