ActiveRecord::Base.scopes includes all scopes defined in all subclasses

ActiveRecord::Base.scopes which is defined as a class_attribute in NamedScope is shared by all classes that inherit from ActiveRecord::Base. ActiveRecord::Base#scope does not dup the scopes class_attribute hash for every class. I'm guessing having every model share every scope is not the intended functionality, but I may be missing something obvious. Attached is a patch for with a test and the code that makes that test pass.