add simple test that allows to reproduce low level invalidation bug.

we might remove this test later, but it is usefull to have
several people working on this problem.

This test should not be started by default and should be used with
activity_node options

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@35396 20353a03-c40f-0410-a6d1-a30d3c3de9de