The 1.34.0-wmf.16 version of MediaWiki is blocked[0].
The new version can't proceed to group0[1] 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
[0]. <https://phabricator.wikimedia.org/T220741>
[1]. <https://tools.wmflabs.org/versions/>