Apparently also breaking some local JS, including LangSelect for some people (and that's quite an important one).
Quoting from the URL.
<p>Fecha y hora: 15/01/2013 21:12:43</p>
<p>'''Error: TypeError: previousLanguages.push is not a function'''</p>
<p>Archivo de origen: https://bits.wikimedia.org/meta.wikimedia.org/load.php?debug=false&lang=en&modules=ext.centralNotice.bannerController%7Cext.translate%7Cext.uls.displaysettings%2Cgeoclient%2Cime%2Cinit%2Cinputsettings%2Clanguagesettings%2Cpreferences%2Cwebfonts%7Cext.uls.webfonts.repository%7Cjquery.byteLength%2CbyteLimit%2Cclient%2Ccookie%2Ci18n%2Cime%2CjStorage%2Cjson%2CmwExtension%2CtextSelection%2Ctipsy%2Culs%2Cwebfonts%7Cmediawiki.Uri%2Capi%2Cnotify%2Cuser%2Cutil%7Cmediawiki.action.edit%7Cmediawiki.legacy.ajax%2Cwikibits%7Cmediawiki.page.startup&skin=monobook&version=20130115T091957Z&*</p>
<p>Línea: 27</p>
Which is:
previousLanguages.push(currentLang);mw.uls.setPreviousLanguages(previousLanguages);$ulsTrigger.tipsy({gravity:'n',delayOut:3000,html:true,fade:true,trigger:'manual',title:function(){var link;link=$('<a>').text($.uls.data.getAutonym(previousLang)).attr({href:'#','class':'uls-prevlang-link',lang:previousLang,dir:$.uls.data.getDir(previousLang)});link=$('<div>').html(link).html();return $.i18n('ext-uls-undo-language-tooltip-text',link);}});function showTipsy(timeout){var tipsyTimer=0;$ulsTrigger.tipsy('show');$('.tipsy').on('mouseover',function(){window.clearTimeout(tipsyTimer);});$('.tipsy').on('mouseout',function(){tipsyTimer=window.setTimeout(function(){hideTipsy();},timeout);});$('a.uls-prevlang-link').on('click',function(){mw.uls.changeLanguage($(this).attr('lang'));});tipsyTimer=window.setTimeout(function(){hideTipsy();},timeout);}function hideTipsy(){$ulsTrigger.tipsy('hide');}showTipsy(6000);$ulsTrigger.on('mouseover',function(){if(!$ulsTrigger.data('uls').shown){showTipsy(3000);}
Version: master
Severity: normal
URL: https://meta.wikimedia.org/w/index.php?diff=5051434&oldid=5051328&rcid=3834461