We need to insert null revisions into the client for Wikibase changes.
This will allow changes to show up in the article history and display correctly in the watchlist.
In the simplest implementation, a null revision is treated as being done by IP user 127.0.0.1, similar to what Special:Import does.
It's not pretty, so we'll need a separate to-do to handle displaying external users and changes in a nicer way, everywhere in the client.
Version: master
Severity: major