Description of problem:
When using the following script:

/usr/bin/zenity --warning --title="CONSENT BANNER" --text "`cat /etc/issue`" --width=750
answer=$?
if [ "$answer" == "1" ] ; then
       exit 1
fi

in /etc/gdm/PreSession/Default, disagreeing with the dialog box no longer kicks user out to login screen.  In RHEL 5, this functionality allowed the admin to provide an EULA to the user, who had to agree with it to continue the login and would be logged out if they disagreed, in RHEL 6 the prompt may appear but does not kick the user out of disagreement.  We were able to work around this by putting in in the Xsession file however it appears the functionality in GDM may have changed.

Version-Release number of selected component (if applicable):
gdm-2.30.4-33.el6_2.x86_64 

How reproducible:
Every time.

Steps to Reproduce:
1. Place the above script in /etc/gdm/PreSession/Default in RHEL 5
2. Login as the user
3. Disagree with the EULA and get kicked out
4. Do the same in RHEL 6 and see the behavior is no longer honored
  
Actual results:
Customers allowed to get into the OS even after disagreement with EULA.

Expected results:
Customers kicked out to login screen when disagreeing with the EULA.

Additional info: