CMFActivity.ActivityTool: Fix ambiguous method name.

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

00:48:21

passed ERP5.PerformanceTest-Master

00:24:20

failed ERP5.UnitTest-Master

04:03:52

failed ERP5.UnitTest-Master.Medusa

01:34:25

passed SlapOS.Eggs.UnitTest-Master.Python2

00:11:42

passed SlapOS.Eggs.UnitTest-Master.Python3

00:12:31