weichen
e9673cad88
Why: on slow runners the orphaned http child of a stopped stub lingers a few hundred milliseconds past the parent's exit (ppid-watch suicide), and the immediately following start - notably the U2 rollback restart - classified the unparented listener as a foreign occupant and refused to start (CI run 3774). Evidence: test_svc_u2/identity/svc suites 82 OK locally with the wait in both stop paths. Impact: adds <=3s bounded wait in do_stop/do_stop_quiet after SIGTERM cleanup; no behavior change when the port is already free.