The Source Wiki Editing feature is now disabled in production. It was enabled and available to our users from roughly 13:00 UTC on July 22 until 13:30 UTC on July 24.
When creating the graphs for T226513, I discovered that we have a high number of failures for source wiki editing and deletion, and zero successes. Looking at the source wiki page history for the last few days of FileImporter imports confirmed that there seem to be no successful edits or deletes.
Reading code and looking for matching events in the production logs, there are several strings I searched for:
* "Failed to get centralauthtoken": 0
* "user can't use CentralAuth": 0
* "failed to get CSRF token": 0
* "failed to do remote request": 0
* "failed to do post import edit": 16
* "failed to do post import delete": 7
This is really bizarre, because the only code path I see which can cause this outcome without leaving other logs is that the final POST request to perform the edit or delete action succeeds at the HTTP level (avoiding throwing the exception) but returns malformed JSON which cannot be `json_decode`'d.
== Actions to take
 Add missing logging to the place TODO
 Try reproducing the issue on beta cluster
 Re-enable the feature on testwiki and test2wiki, and investigate the issue there