-- 2.7.2 — BUG#6 filed upstream. Documentation-only.
--
-- No shippable code change: the binary is byte-identical to 2.7.1 (the only
-- src/ edit is a doc comment). No wire change (v8), no SQL surface change,
-- no REINDEX.
--
-- The BUG#6 root-cause analysis and one-line core fix that 2.7.1 verified
-- have been REPORTED UPSTREAM on pgsql-hackers (2026-09-08 17:28 UTC):
--   https://www.postgresql.org/message-id/0498c10f-839b-4f68-9994-c29b454e55a4%40app.fastmail.com
--
-- The filed patch's execTuples.c hunk is identical to the one verified here
-- by A/B build; the filed version additionally adds a core regression test to
-- src/test/regress/{sql,expected}/gist.*. That added test was checked against
-- both builds: it reports ctid_matches = 1 on unpatched 18.4 and 5 on the
-- patched build, so it genuinely gates the fix rather than passing vacuously.
--
-- docs/FILTERING.md and the knn_scan_ctid_projection_upstream_limitation test
-- now carry the thread link. That test still asserts the CURRENT (broken)
-- behaviour, so it will FAIL once a fixed PostgreSQL reaches CI -- which is
-- the intended signal to flip the assertion (gated on the fixing version) and
-- relax the docs, NOT a regression in this AM.
--
-- Until a fixed PostgreSQL ships, the workaround is unchanged and remains a
-- proven necessity, not a preference: MATERIALIZED CTEs, text casts inside a
-- subquery, and extra subquery nesting were all tested and all still yield
-- the sentinel. Chain on your own key column, or use turbovec.knn().
--
-- This migration is intentionally empty.