testTask: make sure rules are indexed before tests start

Otherwise, first test may fail if '--random_activity_priority=' option is used.

product/ERP5/tests/testTask.py

@@ -549,6 +549,7 @@ class TestTask(TestTaskMixin, ERP5TypeTestCase):
 
   def afterSetUp(self):
     self.validateRules()
+    self.stepTic()
 
   def getTitle(self):
     return "Task"