Hmmm, If I understand what your saying then the child should exit after some amount of time.? By observing the "ping timeout" debug message I can see that the child is still running after the TERM is sent. I waited about 5 minutes and it never died. I decided to hammer the child with TERM's just to see what would happen. I drove the CPU to 0% idle with:

do 
    {
    $check_kill = kill ("TERM",$child_pid_to_kill);
    }        
until $check_kill > 0;
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and it never died.