Version 4.2 backward incompatibility?

[Norman Schmidt Jr]

In early May, I set up a Debian box with FAI official Debian package 
(2.0.8), configured it to generate ISOs using a partial mirror made with 
fai-mirror. It worked as a charm, until a couple of days ago.
I needed to add some packages and change a couple of files, so I needed 
to fai-make-nfsroot and fai-mirror. After that, any ISO I generate start 
to boots but stops with some errors:
http://i.imgur.com/oZVDPxo.png
While investigating, I noticed the ISOs I generate days ago were 
reporting version 4.1.1 or 4.0.8 during installation, and the new ones 
generated after that nfsroot and mirror rebuilding were reporting 
version 4.2.
The only way I could get a generated ISOs to boot and install correctly 
again was commenting off the FAI repository from 
/etc/fai/apt/sources.list, and rebuilding the nfsroot and the local 
mirror. This way it uses FAI 4.0.8 from the Debian repository, and not 
4.2 from FAI repository, and everything works.
So Im guessing there is some backward incompatibility between versions 
<= 4.1.1 and 4.2?
Norm