SecurityTestCase: better assertion failure for transition

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Status Job ID Name Coverage
  External
passed ERP5.CodingStyleTest-Master

01:02:31

passed ERP5.UnitTest-Master

01:31:33

failed ERP5.UnitTest-Zope2

04:10:11

passed SlapOS.Eggs.UnitTest-Master.Python2

00:18:54

passed SlapOS.Eggs.UnitTest-Master.Python3

00:14:13

passed Wendelin.UnitTest-Master

03:44:15