Plack::Middleware::Scrutiny::IOWrap - Wrap IO Handles
The child needs to be sent the environment,
$env has some IO handle-like thingts that aren't so easy to serialize.
[editors note: WHY do we have to send it back and forth?
Can we just fork with it?].
So the parent replaces those with an instance of
which just transmits the result of the methods accross the pipe.