The new behavior can be found in this commit, the line is highlighted

https://github.com/MariaDB/server/commit/09bf45a89ee23adc7ce05c46ba859a74b1367f92#diff-1ace7ee02edfe8a4386a6b3c8e6e602c154303e43d13246ecbf9584d6d9994b8R528

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Yours truly,

Nikita Malyavin