wfMessage('mainpage')->inContentLanguage() always gives the content language, even if it is overrriden by $wgForceUIMsgAsContentMsg
php maintenance/eval.php
$wgContLang = Language::factory('en');
$wgLang = Language::factory('fr');
$wgForceUIMsgAsContentMsg[] = 'mainpage';
echo wfMsgForContent('mainpage');
Accueil
echo wfMessage('mainpage')->inContentLanguage()->text();
Main Page
Version: 1.17.x
Severity: normal