I hit this when testing https://gerrit.wikimedia.org/r/#/c/172925/ against https://www.mediawiki.org/wiki/VisualEditor/Feedback .
So far I haven't retested against master, since the import is pretty slow. I suspect it will be present there.
Command was:
mwscript extensions/Flow/maintenance/convertLqt.php --wiki=wiki User_talk:VE_Feedback_1 --allowunknownusernames 1 --remoteapi=https://www.mediawiki.org/w/api.php --srcpage=VisualEditor/Feedback --verbose
Log is https://phabricator.wikimedia.org/P97 .
Version: unspecified
Severity: normal