* forks setup (script, sock fds indicated in env)
* fd0, fd1, fd2: from-outer
* other fd: call(client-end)(fake)
* reaps setup (and reports error)
* (implicitly releases lock)
*
* forks setup (script, sock fds indicated in env)
* fd0, fd1, fd2: from-outer
* other fd: call(client-end)(fake)
* reaps setup (and reports error)
* (implicitly releases lock)
*