To prevent T288724 from happening again, we should test at some level that entity namespaces have the right `"defaultcontentmodel"` in the `action=query&meta=siteinfo&siprop=namespaces` API response, since Pywikibot and probably others rely on this information.
A browser test or API integration test is probably the best option for this, though I’m not sure if we can make those tests work on any wiki, even if it doesn’t have local entities (e.g. how Commons is a Wikibase repository but has no namespaces with `wikibase-item` or `wikibase-property` default content model). If all else fails, we could write a test that specifically targets Wikidata (where we know the right namespaces), and run it nightly against (Beta) Wikidata.
**Acceptance criteria 🏕️🌟(18 August 2021)**
[] API integration test for Wikibase covering the defaultcontentmodel case