test_head_runs_official_image_not_bitnamilegacy hardcoded the migration-era pin
discourse/discourse:3.5.3 and went stale on the first legitimate app bump
(2026.7.1, weekly 2026-08-03 — caught by verify run 2: the upgrade converged,
head image was discourse/discourse:2026.7.1, only the frozen pin failed). The
guarded property is the image FAMILY (official vs bitnamilegacy), not a frozen
version — now asserts the discourse/discourse: prefix. Not weakened: the
bitnami-leak check + official-prefix check together still assert exactly the
migration faithfulness; the concrete head pin is exercised by the deploy.