The autouse fixture neutralised gateway discovery and the systemd branch
but not the launchd one. On a macOS host `_restart_macos_launchd_gateways`
derives its labels from the profile layout, so a default profile alone
hands it `ai.hermes.gateway`, the label never "comes back", and nine
unrelated update tests exit 1 with "Update incomplete". No OS is faked:
the seam is stubbed the same way test_update_fleet_restart_pending does.
f0fd0650b5