Changing the slug of an entity in the UI

[crazyscientist]

Steps to reproduce

1. Create a schema with arbitrary slug.
2. Create an entity with an arbitrary slug.
3. Edit/Update the entity

• Change the slug
• (Optional) Change the name

4. Navigate to the "History" tab (this causes /api/changes/entity/<schema_slug>/<unknown_entity_slug> replies with status 500 #128 to happen)

Expected behavior

The entity gets updated internally.

Among other expected side effects:

• If the name was changed, the new name should appear in the breadcrumbs.
• When the slug gets changed, a subsequent switch to the "History" tab is successful.