This should fix testBPMEvaluation __setstate__ recursion.

I have a patch ready if/when we decide that we need to perform this kind of
change dynamically inside ERP5Type.Utils.PersistentMigrationMixin


git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@39653 20353a03-c40f-0410-a6d1-a30d3c3de9de