UpdateGraph from GraphDiff raises an incomplete DbUpdateConcurrencyException

Question

I am using EF6 and GraphDiff 2.0.1. I want to check for DbUpdateConcurrencyException when I save an outdated entry. When I do this without an UpdateGraph: no problem, EF raises the exception.

try
{
    var dbEntry = Context.Persons.SingleOrDefault(p => p.PersonId == 
        disconnectedEntry.PersonId);
    dbEntry.Name = disconnectedEntry.Name;
    Context.Entry(dbEntry).OriginalValues["RowVersion"] = disconnectedEntry.RowVersion;
    DbContext.SaveChanges();
}
catch (DbUpdateConcurrencyException ex)
{
    // Exception thrown as expected.
}

I used the solution described here to achieve this: EF not throwing DbUpdateConcurrencyException despite conflicting updates

The problem is: if I use an UpdateGraph from GraphDiff before the SaveChanges from EF: UpdateGraph raises an incomplete DbUpdateConcurrencyException. Indeed, the exception doesn't contain Entries.

try
{
    DbContext.UpdateGraph(disconnectedEntry);
    DbContext.SaveChanges();
}
catch (DbUpdateConcurrencyException ex)
{
    // Exception thrown as expected. But ex is incomplete
}

I am surprised that UpdateGraph raises this exception. According to me, UpdateGraph updates the connected entry, but doesn't save. So, it should do nothing and let EF do the job.

Is there a way to avoid that UpdateGraph raises the exception. At least, it could be great if it raises a complete one.