We attempted to fix this with a change to the config file: https://gerrit.wikimedia.org/r/c/operations/mediawiki-config/+/570892
But this fix had to be reverted after applying it to production: https://gerrit.wikimedia.org/r/c/operations/mediawiki-config/+/570901
We suspect it had to be reverted due to it causing problems and not just unfortunate co-incidence. It only caused a small number of errors: https://logstash.wikimedia.org/app/kibana#/dashboard/0a9ecdc0-b6dc-11e8-9d8f-dbc23b470465?_g=h@961394c&_a=h@a3fe00c
However we fired about 40 icinga alerts of app servers see this copy of the log from #wikimedia-operations {P10365}
And according to reports took the wikis down.
TODO: fill in table
Below is a table of what we presume the config was actually set to at different times due to this typo:
| **Time** | 3rd February (all wikis on .16) |
| **Actual value on group0** |
| **Actual value on group1** |
| **Actual value on group2** |