Process might be on the debugger children list without P_TREE_ORPHANED set if e.g.
- process is grandchild of the debugger,
- process parent (child of the debugger) exited.
Then reapper is recorded as o_pptr for the process, but the process itself is not put on the orhpan list of reapper, since it is killed anyway.
This situation is caught if instead of P_TREE_ORPHANED, we check for jobc_parent() equal to the debugger, and ignore the process for job control counting otherwise.