Remove internal deprecation

lib/active_fedora/associations.rb

@@ -227,7 +227,8 @@ def association_accessor_methods(reflection, association_proxy_class)
           end
 
           redefine_method("#{reflection.name}_id=") do |new_value|
-            obj =  new_value.blank? ? nil : reflection.klass.find(new_value)
+            options = reflection.klass == ActiveFedora::Base ? {cast: true} : {}
+            obj =  new_value.blank? ? nil : reflection.klass.find(new_value, options)
             send("#{reflection.name}=", obj)
           end
           redefine_method("#{reflection.name}_id") do 

spec/integration/associations_spec.rb

@@ -473,6 +473,32 @@ class Topic < ActiveFedora::Base
     end
   end
 
+  describe "belongs_to when class_name is ActiveFedora::Base" do
+    before :all do
+      class Textbook < ActiveFedora::Base
+        belongs_to :container, :property=>:is_part_of, :class_name=>'ActiveFedora::Base'
+      end
+      class Shelf < ActiveFedora::Base; end
+    end
+
+    after :all do
+      Object.send(:remove_const, :Textbook)
+      Object.send(:remove_const, :Shelf)
+    end
+
+    after do
+      shelf.destroy
+    end
+
+    let(:shelf) { Shelf.create}
+    subject { Textbook.new }
+
+    it "Should not raise a deprecation message" do
+      Deprecation.should_not_receive(:warn) # a deprecation in 6.6.0 that's going away in 7.0.0
+      subject.container_id =  shelf.id
+    end
+  end
+
   describe "single direction habtm" do
     before :all do
       class Course < ActiveFedora::Base
@@ -860,4 +886,4 @@ class ComplexCollection < SimpleCollection
       end
     end
   end
-end
+end