start-tty-listener behavior changes ?

Has something changed regarding the (perceived) behavior of start-tty- 
listener in LWL from 4.4.x -> 5.0 ?

Let me explain:

Starting from a TTY image, creating using (save-image "lispworks- 
tty" :environment nil)
I make a general purpose delivered server image using, essentially,

(deliver #'(lambda ()
                   (lw-base:delivered-image-startup)
                   (start-tty-listener))
          "lw-base"
          0
          :multiprocessing t
          :keep-pretty-printer t
          :keep-debug-mode t
          :keep-conditions :all
          :interface nil)

Normally, I then run this image under screen.
This doesn't work any more in the specific case that I am using.

More specifically, I can start the image manually directly, or I can  
start screen,
start the image manually inside screen, detach and re-attach - all  
this works.

However, I normally call screen programmatically from within a server  
startup script
using screen -d -m <command>
The screen -L option shows that the image does start up, but the  
listener process
started by (start-tty-listener) seems to return or stop immediately,  
causing the image to quit, silently.

This used to work on LWL 4.4.x and it still works for LWM 5.0 on Mac  
OS X (Server) 10.3.x / 10.4.x

Details of the Linux system:

Red Hat Enterprise Linux ES release 4 (Nahant Update 2)
Linux mother.intern.beta9.be 2.6.9-22.0.2.ELsmp #1 SMP Thu Jan 5  
17:11:56 EST 2006 x86_64 x86_64 x86_64 GNU/Linux

TIA,

Sven