On https://gerrit.wikimedia.org/r/#/c/274025/, various Wikibase view seems to rely on setting the user language via $wgLang instead of RequestContext.
0d6c80cc5f695 is not the only one apparently. After that one is fixed, 47 more tests started failing in Wikibase:
Here is the first one:
23:38:42 There were 47 failures: 23:38:42 23:38:42 1) Wikibase\View\Tests\EntityTermsViewTest::testGetHtml_isMarkedAsEmptyValue 23:38:42 Failed asserting that '<div class="wikibase-entitytermsview"> 23:38:42 <div class="wikibase-entitytermsview-heading"> 23:38:42 <div class="wikibase-entitytermsview-heading-description wb-empty">No description defined</div> 23:38:42 <div class="wikibase-entitytermsview-heading-aliases wb-empty"><ul class="wikibase-entitytermsview-aliases">No aliases defined</ul></div> 23:38:42 </div> 23:38:42 <EDITSECTION> 23:38:42 <div class="wikibase-entitytermsview-entitytermsforlanguagelistview $UNIQc5595ffb90b27121#1$"></div> 23:38:42 </div>' contains "(wikibase-description-empty)". 23:38:42 23:38:42 /mnt/jenkins-workspace/workspace/mediawiki-extensions-hhvm/src/extensions/Wikidata/extensions/Wikibase/view/tests/phpunit/EntityTermsViewTest.php:124 23:38:42 /mnt/jenkins-workspace/workspace/mediawiki-extensions-hhvm/src/tests/phpunit/MediaWikiTestCase.php:147