The pipeline gated on `target_arch`, which is the same variable
build-all-versions and build-all-versions-install-deps gate on. A manual run
passing `target_arch=arm64` to reach the repair therefore also matched both of
those and started a full arm64 rebuild alongside it.
Every other pipeline here gates on a variable named after itself
(`process_cran_updates`, `weekly_audit_missing`, `weekly_rebuild_missing`), so
follow that and gate on `repair_built_stamp`. Record the collision and the exact
invocation in the header so the next pipeline added here does not repeat it.