The most common case of 277470 for me locally is this one:
There was 1 failure: 1) OutputPageTest::testGetJsVarsAboutPageLang with data set #24 ('sr-ec', array(6, 'Example'), 'sr', 'sr', 'sr-ec') HTTP request blocked: https://commons.wikimedia.org/w/api.php?titles=File%3AExample&iiprop=timestamp%7Cuser%7Ccomment%7Curl%7Csize%7Csha1%7Cmetadata%7Cmime%7Cmediatype%7Cextmetadata&prop=imageinfo&iimetadataversion=2&iiextmetadatamultilang=1&format=json&action=query&redirects=true&uselang=sr by ForeignAPIRepo::httpGet. Use MockHttpTrait.