> that race condition, if thats what this is, is likely not OS X
> specific.  the child process could complete or close its fds before we
> reach that code on any OS.  We either need to guard these
> io.open(p2c*...) lines against EBADF OSError's or we should create the
> io wrappers before _execute_child() is called.

Creating them before _execute_child() is the obvious and simple solution
(if my diagnosis is correct). Is there any downside to doing so?