The 1.34.0-wmf.16 version of MediaWiki is blocked.
The new version can't proceed to group0 until this issue is resolved:
* serialize(): "" returned as member variable from __sleep() but does
not exist - https://phabricator.wikimedia.org/T229366
Once this issue is resolved train can resume. If this issue is
resolved on a Friday the train will resume Monday.
Thank you for your help resolving these issues!
-- Your unassuming train minion