On the error path posix.sh writes the result, relaunches the app, and then
sleeps 1.5 s to confirm the launch took. A relaunched app that boots fast logs
`detached update FAILED` inside that window, and the spec checked for a live
posix.sh right away. On #124878 the app logged at 08:34:06.565, about 0.5 s
after it launched, the check ran at 08:34:07.16, and posix.sh was still in
`sleep 1.5`. The spec now polls for up to 30 s.
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