9.0 to 9.1 upgrade broke cups but has easy fix
I used swaret to upgrade from 9.0 to 9.1. And I had installed cups for printing. After the upgrade cupsd was running but applications that print to lpr wouldn't. This was because the symbolic links that pointed from lpr to lpr_cups were reset back to use lpr_lprng (the default print manager).
A quick reinstall of cups using swaret fixed everything...
swaret --reinstall cups