The record and relation-child thumb routes now also serve the thumbnail
of a public JPEG, PNG, GIF or WebP file, under the same record or
pending-session scope and D-10 headers as a protected one, so the admin
can preview a public image whose public URL does not load. The download
routes still answer 404 for every public file, and a public non-image
thumb stays 404.
TestPublicImageThumb covers owner, foreign and hidden records, image
types, a public row under a protected field, another admin's pending
upload and the relation-child route.
Jakub Zych
e4302bf60b