Foomatic.getPPD() should use the same method as getPrinterFromCupsDevice() for matching IEEE 1284 IDs to models. Currently, only getPrinterFromCupsDevice() knows how to search through the models list case-insensitively in the case of the IEEE 1284 Device ID not being known.
Fixed in foomatic.py:1.50.
Fixed in update: system-config-printer-0.7.45-1.fc6