Vendor-provided .ppd does not work (Konica Minolta mc2450)

Konica Minolta supports a linux driver .ppd for its magicolor 2450 printer[0]. When I use the CUPS webinterface to upload this .ppd, it results in CUPS crashing (not being accessible on localhost:631 anymore) right after the authentication dialog when I hit "Add Printer". I tried the same with a different .ppd (ljet4 from linuxprinting.org) and it worked, but I don't know if this is because ljet4 already exists by default. I don't have any other third-party-ppds to try.

In case uploading works with other .ppds, this debug information for my specific case might be useful:

For testing, I explicitely changed every occurence of "KONICA MINOLTA" in the english km2450np.ppd to "KonicaMinolta", as to not get hit by bug #33545. Furthermore, I saved the ppd as iso-8859-1 (as specified in the .ppd), just in case utf-8 is giving problems. Both give the same problem.

Steps to reproduce:
sudo apt-get remove --purge cupsys
sudo rm -rf /var/cache/cups /var/run/cups
sudo apt-get install cupsys
sudo adduser cupsys shadow
sudo cp /etc/cups/cupsd.conf /etc/cups/cupsd.conf.orig
sudo sed -e "s/LogLevel warning/LogLevel debug/" /etc/cups/cupsd.conf.orig > /etc/cups/cupsd.conf
sudo /etc/init.d/cupsys restart
-> go to http://localhost:631 and add the printer.

I will attach the end of /var/log/cups/error_log, although it does not seem to contain any hint.

This might be an upstream bug with CUPS 1.2, but I suppose you are in good contact with upstream as to forward it in that case. The same .ppd worked with CUPS in Breezy.

0: http://printer.konicaminolta.com/support/current_printers/mc2450_sup.htm (look at the end of the page)