A mtr failure in rpl.rpl_mariadb_slave_capability mismatch:

-slave-relay-bin.000005	#	Query	#	#	BEGIN
+slave-relay-bin.000005	#	Query	#	#	set foreign_key_checks=1, check_constraint_checks=1; BEGIN

was fixed by {{80544a58}}, and without any check for {{flags_inited}}
which is a pattern in the sources.

This ticket therefore merely makes sure through an assert that a
relation between the two remain in {{Query_log_event::pack_info}}.