Clear IdentityMap before continue this test, we can do this here because...

Clear IdentityMap before continue this test, we can do this here because store_full_sti_class is not supposed to change during "runtime".

activerecord/test/cases/associations/eager_load_includes_full_sti_class_test.rb

@@ -27,6 +27,7 @@ def test_class_names
     post = Namespaced::Post.find_by_title( 'Great stuff', :include => :tagging )
     assert_nil post.tagging
 
+    ActiveRecord::IdentityMap.clear
     ActiveRecord::Base.store_full_sti_class = true
     post = Namespaced::Post.find_by_title( 'Great stuff', :include => :tagging )
     assert_instance_of Tagging, post.tagging