What: run_bounded's no-perl branch starts the probe under bash job control (set -m), so it gets its own process group and the timeout's kill -KILL -- -pid reaches its children.
Why: without perl the probe stayed in the caller's group, the group kill failed, and a hung hermes --version / update --help left its python child running.
Red: pre-fix posix.sh fails test_timed_out_probe_is_killed_with_its_whole_process_tree[absent] (grandchild alive after rc=124). Green: both [present] and [absent] pass.
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