Hello,
Due to some mistake I made during the Jenkins job overhaul last year, the PHPUnit jobs were no more using $wgDevelopmentWarnings. That is now fixed.
I have also enabled $wgShowExceptionDetails per bug 43059.
If that cause any serious trouble, shell users could change the setting file on gallium at:
/var/lib/jenkins/jobs/_shared/ExtraSettings.php
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