Forget about old memoize immutable behavior

activesupport/test/memoizable_test.rb

@@ -124,16 +124,6 @@ def test_memoization_with_nil_value
     assert_equal 1, @person.age_calls
   end
 
-  def test_memorized_results_are_immutable
-    # This is purely a performance enhancement that we can revisit once the rest of
-    # the code is in place. Ideally, we'd be able to do memoization in a freeze-friendly
-    # way without amc hacks
-    pending do
-      assert_equal "Josh", @person.name
-      assert_raise(ActiveSupport::FrozenObjectError) { @person.name.gsub!("Josh", "Gosh") }
-    end
-  end
-
   def test_reloadable
     counter = @calculator.counter
     assert_equal 1, @calculator.counter