[Maria-developers] MariaDB 10.0.14 got rid of replication safety warning without warning in release notes?

Hi, I see that in MariaDB 10.0.14 Michael disabled replication safety warning for the case of INSERT ON DUPLICATE KEY UPDATE with several unique keys with a comment "We should assume that the store engine will report the first duplicate key for this case." http://bazaar.launchpad.net/~maria-captains/maria/10.0/revision/4400.1.3 What does that mean? Which key is "the first duplicate key" and why MariaDB relies on an engine behavior which AFAIK is not guaranteed? And why this serious change in behavior wasn't mentioned in the Release Notes? On the related note Release Notes mention the error log flood protection. Why it's not behind flag? How should I disable the feature and get back to the old behavior? Thank you, Pavel