-- Drop reference_only, the contract half of the pair MUL-7072 started. Since that
-- release a bare body mention of an issue key writes no link row at all, and no
-- query reads or writes this column. It may only run once every instance of the
-- previous release is gone: an older instance still names the column in its link
-- INSERT and would fail on every link write against this schema.
--
-- The DELETE repeats as a mop-up. Migration 462 cleared the historical hidden
-- rows, but instances still serving during that rollout could write a few more,
-- and once the column is gone such a row becomes indistinguishable from a real
-- link — visible in the issue's PR list and, while its PR is in flight, blocking
-- the issue from auto-advancing.
DELETE FROM issue_pull_request WHERE reference_only;
DELETE FROM issue_vcs_pull_request WHERE reference_only;

ALTER TABLE issue_pull_request DROP COLUMN reference_only;
ALTER TABLE issue_vcs_pull_request DROP COLUMN reference_only;