The interim solution is to relax the sandboxing policy in CUPS 2.0, so that it behaves like it used to. Of course, it would be better if PaperCut fixed the underlying problem in their software.
The short version of what to do is:
sudo sh -c 'echo "Sandboxing Relaxed" >> /etc/cups/cups-files.conf'
sudo launchctl stop org.cups.cupsd
The long version can be found at: