The deployment of 1.31.0-wmf.22 revealed a critical bug[1] immediately after I pushed the new branch to group1 wikis. Group1 was rolled back to wmf.21 pending the resolution of T187942. Refer to Phabricator for details and discussion. I will attempt to resume the train later today, assuming blockers[2] have been resolved.

1. Replication lag detection broken in wmf.22 https://phabricator.wikimedia.org/T187942 2. 1.31.0-wmf.22 deployment blockers https://phabricator.wikimedia.org/T183961