problem

When segments are fetched for processing transaction not in play.
that resulted in failing test of quality analysis in some plugins

reason

The FOR UPDATE clause of SELECT applies only when autocommit is set to 0 or the SELECT is enclosed in a transaction. A lock is acquired on the rows, and other transactions are prevented from writing the rows, acquire locks, and from reading them (unless their isolation level is READ UNCOMMITTED).
See https://mariadb.com/kb/en/for-update/