class ActiveRecord::Associations::Preloader::Association

def build_scope
  scope = klass.scope_for_association
  if reflection.type && !reflection.through_reflection?
    scope.where!(reflection.type => model.polymorphic_name)
  end
  scope.merge!(reflection_scope) unless reflection_scope.empty_scope?
  if preload_scope && !preload_scope.empty_scope?
    scope.merge!(preload_scope)
  end
  cascade_strict_loading(scope)
end