Prior to fdfa8052d1, it was possible to create an item in a feed
library using Add Item by Identifier. If you did that, and then copied
it to a collection in your personal library, it would somehow end up
with an owl:sameAs relation to a `/users/local` URI (probably because
the URI functions don't work properly on a feed library).
This will clean up such relations in a schema update.
595ba396ef