mountroot prompt not working

[Simon 'corecode' Schubert]

In multiple recent install/upgrade/troubleshoot processes with 
release2.4 cd images, the mountroot prompt did not work.  Instead of 
staying at the prompt, the system would directly jump into ddb, and a 
"c" also would not take you back to the prompt but instead proceed to 
restart the system.  VERY BAD.