Last modified: 2014-11-11 11:22:20 UTC
When saving an entity without changing it, the MediaWiki storage layer (WikiPage) will not create a new revision (it performs a "null edit"). However, WikiPageEntityStore::saveEntity will still signal an 'entityUpdated' event to listeners, which causes CachingEntityRevisionLookup to push the new version of the entity (which should be the same as the old) into the cache. If null edits only happen when they should, this should not be a problem - it would just cause a bit of unnecessary memcached traffic for null edits. However, in case of "accidental" null-edits caused by false positives reported by EntityContent::equals, caching the new (actually different) version of the entity even though it did not get save to the database adds to the confusion.
