What: update_custody.run's in-update (Windows) branch kills the child's tree (taskkill /T /F) on a
timeout, then drains its output for at most 5 s and detaches pipes a survivor still holds.
Why: it killed only git.exe and waited unbounded on git-remote-https, which inherits the pipes.
Red/green: pre-fix run(sh -c 'sleep 20 & sleep 20', timeout=0.5) -> AssertionError (waited); fixed -> passed.
1057d2111e