I'm seeing some browser test failures surfacing which are preventing merges in Popups and RelatedArticles repos. I've not investigated too deeply but I suspect this is a false positive as they seem linked to the migration to OOUI in T148252:
- https://integration.wikimedia.org/ci/job/mwext-mw-selenium/10994/console
- https://integration.wikimedia.org/ci/job/selenium-RelatedArticles/183/BROWSER=chrome,MEDIAWIKI_ENVIRONMENT=beta-desktop,PLATFORM=Linux,label=contintLabsSlave%20&&%20UbuntuTrusty/testReport/(root)/ReadMore/ReadMore_is_present_when_enabled_as_a_BetaFeature/
Since the editing team is closest to this code at the moment, they might be best placed to investigate these and check that nothing is broken and update the browser tests/retain attributes that were previously expected.