Last failure was in 12th of June, almost 1 month ago https://ge.xwiki.org/scans/tests?search.relativeStartTime=P28D&search.timeZoneId=Europe%2FBucharest&tests.container=org.xwiki.realtime.wysiwyg.test.ui.AllIT$NestedRealtimeWYSIWYGEditorIT&tests.test=editAlone# so it may have been fixed.