Description of problem:
system-config-printer doesn't display dnssd-discovered printers in the New Printer wizard when run as an ordinary user.

Running system-config-printer --debug:

Connected as user james
refresh
Created subscription 144
<monitor.Monitor instance at 0x1b705f0>: printers and jobs lists provided
update_jobs
Authentication pass: 1
Authentication: password callback set
Authentication pass: 1
Authentication: password callback set
Authentication pass: 1
Authentication: password callback set
get_notifications
update_jobs
Calling <bound method NewPrinterGUI.fetchDevices of <__main__.NewPrinterGUI instance at 0x1b5d518>>
fetchDevices
Caught exception 'module' object has no attribute 'WITH_POLKIT_1'
queryPPDs
Lock acquired for PPDs thread
Connecting (PPDs)
Fetching PPDs
PPDs thread started
Caught non-fatal exception.  Traceback:
File "/usr/share/system-config-printer/system-config-printer.py", line 5022, in got_devices
    raise exception
AttributeError: 'module' object has no attribute 'WITH_POLKIT_1'
Continuing anyway..
Closing connection (PPDs)
Releasing PPDs lock
Command canceled
Canceled subscription 144
<monitor.Monitor instance at 0x1b705f0> exited


Version-Release number of selected component (if applicable):
avahi-0.6.25-3.fc11.x86_64
system-config-printer-1.1.12-8.fc11.x86_64
PolicyKit-0.9-6.fc11.x86_64
cups-1.4.0-2.fc11.x86_64

How reproducible:
Always.

Steps to Reproduce:
1. Open s-c-p as an ordinary user.
2. Click on new.
3. Wait for discovered printers.
  
Actual results:
No discovered printers, except when run as root.

Expected results:
Discovered printers.