Trying to replicate reported problem with NSub 1.2 and pure virtual classes

NHibernatishExample.cs

    public class NHibernatishExample {
        public interface IRepository { SampleEntity Get(int id); }
        public class SampleEntity {
            public virtual int Id { get; set; }
            public virtual string Name { get; set; }
        }
        public class SomeService {
            private readonly IRepository _repository;
            public SomeService(IRepository repository) { _repository = repository; }
            public SampleEntity DoSomething() {
                return _repository.Get(4);
            }
        }

        [Test]
        public void DoSomething()
        {
            var mockRepository = Substitute.For<IRepository>();
            var fakeEntity = new SampleEntity { Id = 4, Name = "Sample" };
            mockRepository.Get(4).Returns(fakeEntity);

            var result = new SomeService(mockRepository).DoSomething();

            Assert.That(result.Id, Is.EqualTo(4));
            Assert.That(result.Name, Is.EqualTo("Sample"));
        }
    }