AfterTransactionCompletion called twice if a distributed transaction is rolled back

If a session is opened and closed within a System.Transaction transaction, and that transaction is allowed to rollback, there will be two calls to the interceptor's AfterTransactionCompletion().

This is because DistributedTransactionContext.Rollback() will call sessionImplementor.AfterTransactionCompletion(false, null), which will then be called again by the TransactionCompleted event handler attached in AdoNetWithDistributedTransactionFactory.EnlistInDistributedTransactionIfNeeded().