By design task distribution tool may return None if for a given test name and

revision(s) a Test Result has already been completed.
Thus we need to properly handle this use case otherwise simply failing makes "client
side" - i.e. testnode keep trying forever in its _retryRPC calls which
indefinitely blocks further tests executions.

bt5/erp5_test_result/DocumentTemplateItem/portal_components/document.erp5.ERP5ScalabilityDistributor.py

@@ -170,6 +170,7 @@ class ERP5ScalabilityDistributor(ERP5ProjectUnitTestDistributor, object):
          revision, test_name_list, allow_restart,
          test_title=test_title, node_title=node_title,
          project_title=project_title)
+    if created_test_result_tuple is not None:
       # set int_index which is used for sorting to the title of the test case
       # in created_test_result_tuple we have test result relative url and revision
       test_result = portal.restrictedTraverse(created_test_result_tuple[0])