Fixed test

Author: bahusoid

src/NHibernate.Test/Async/NHSpecificTest/GH2043/Fixture.cs

@@ -173,7 +173,6 @@ public async Task UpdateEntityWithInterfaceLookupAsync()
 												.FirstAsync(e => e.Id == _entityWithInterfaceLookupId));
 
 					entityToUpdate.EntityLookup = (IEntityProxy)await (session.LoadAsync(typeof(EntityWithInterfaceProxyDefinition), _entityWithInterfaceProxy2Id));
-					entityToUpdate.EntityLookup.Id = Guid.Empty;
 
 					await (session.UpdateAsync(entityToUpdate));
 					await (session.FlushAsync());

src/NHibernate.Test/NHSpecificTest/GH2043/Fixture.cs

@@ -161,7 +161,6 @@ public void UpdateEntityWithInterfaceLookup()
 												.First(e => e.Id == _entityWithInterfaceLookupId);
 
 					entityToUpdate.EntityLookup = (IEntityProxy)session.Load(typeof(EntityWithInterfaceProxyDefinition), _entityWithInterfaceProxy2Id);
-					entityToUpdate.EntityLookup.Id = Guid.Empty;
 
 					session.Update(entityToUpdate);
 					session.Flush();