RavenDb Session.Advanced.MarkReadOnly bug? repro

MarkReadOnlyBug

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Xunit;

namespace Raven.Tests.Bugs
{
    public class MarkReadOnly : RavenTest
    {
        public class Widget
        {
            public string Id { get; set; }
            public string Property { get; set; }
        }

  	[Fact]
		public void MarkReadOnlyIsNotPersistent()
		{
            const string widgetId = "widgets/1";

			using (var store = NewDocumentStore())
			{
				using (var session = store.OpenSession())
				{
                    var entity = new Widget() { Id = widgetId, Property = "A" };
					session.Store(entity);
					session.SaveChanges();
				}

                // mark readonly
                using (var session = store.OpenSession())
                {
                    var entity = session.Load<Widget>( widgetId );
                    session.Advanced.MarkReadOnly( entity );
                    session.SaveChanges();
                }

                // try changing
                using (var session = store.OpenSession())
                {
                    var entity = session.Load<Widget>( widgetId );
                    entity.Property = "B";

                    Assert.True( session.Advanced.HasChanged( entity ) );
                }
			}
		}
    }
}