Do a minor additional cleanup

To be squashed.

Author: fredericDelaporte

src/NHibernate.Test/BulkManipulation/BulkOperationCleanupActionFixture.cs

@@ -3,7 +3,6 @@
 using System.Linq;
 using NHibernate.Action;
 using NHibernate.Engine;
-using NHibernate.Impl;
 using NHibernate.Metadata;
 using NHibernate.Persister.Entity;
 using NSubstitute;