I updated translatewiki.net code two days ago (after a two week break).
Today I started getting reports that edits are going to wrong pages. I was not able to produce myself, but I found some history which looks wrong.
Click to view the version of December 5th 2017 [?oldid=XXX now shows correct content for this language because cache was purged]. It was supposed to be a two byte change overall (with comment saying some word is replaced). However looking at the diffs or viewing it directly we see a completely unrelated text:
Same unrelated text is also seen on https://translatewiki.net/w/i.php?title=MediaWiki:Cx-notification-deleted-draft/fr&diff=9049005&oldid=9046073
- Wrong content is displayed in page histories diffs both in translatewiki.net and Wikimedia wikis with Translate
- Wrong content is getting exports (not 100% if caused by this)
- It is determined that database is okay, and issue lies with caching of contents.
- It is suspected that there is something wrong with WANObjectCache::getMultiWithUnionSetCallback that causes wrong contents to be cached.
- The problematic caching has been disabled to prevent further corruption of caches. This has been deployed to translatewiki.net and Wikimedia wikis
- Caches and translation pages have been purged on translatewiki.net (multiple times)
- Caches and translation pages have been purged on Wikimedia wikis