The build-fail spec polls 30 s for posix.sh to exit after the relaunched
app reports the outcome. That outcome is "manual" (the Desktop build is
owed), and finish() then runs launch_app (1.5 s acceptance) and
stop_ui leave-window, which sleeps the 15 s shim grace before tearing the
UI down: ~13 s of margin, and a slow Linux runner overran it (posix.sh
still alive at the 30 s mark, run 37619760207). The same code passed this
spec on bb177627828 and c4c2d9d8b54; the head that failed differs only by
a Windows test helper. 90 s keeps "no updater is left running" a real
check without racing the grace window.
69d126be9f