Intermittent failures of trackefflines and persistreco_check_flavourtags tests

test	before (a)	after (b)
Hlt2Conf.test_hlt2_noUT_trackefflines	PASS	FAIL
Hlt2Conf.test_hlt2_trackefflines	PASS	FAIL
Hlt2Conf.test_persistreco_check_flavourtags	PASS	FAIL

LHCb!3963 (merged) introduced instabilities in some Moore tests. An example can be seen from recent build that cannot possibly affect the references is here . Another example where some tests are passing is here.