Description of problem:
   Was using PackageKit to add plugins such as "Allow package downgrade", (something like) "Clean up items that are no longer required", Presto and Repoman to YUM and got the error: 

Traceback (most recent call last):
  File "/usr/share/PackageKit/helpers/yum/yumBackend.py", line 1215, in _get_depends_not_installed
    rc, msgs =  self.yumbase.buildTransaction()
  File "/usr/lib/python2.6/site-packages/yum/__init__.py", line 719, in buildTransaction
    self.plugins.run('postresolve', rescode=rescode, restring=restring)
  File "/usr/lib/python2.6/site-packages/yum/plugins.py", line 179, in run
    func(conduitcls(self, self.base, conf, **kwargs))
  File "/usr/lib/yum-plugins/remove-with-leaves.py", line 71, in postresolve_hook
    if opts.remove_leaves or remove_always:
AttributeError: 'NoneType' object has no attribute 'remove_leaves'

The error message won't go away even if I remove the plugins that I added.  

Version-Release number of selected component (if applicable):
   Fedora 11

How reproducible:
   Won't go away even if I remove the plugins I added. 

Steps to Reproduce:
1. Search for YUM in the search box of "Add/Remove Software" 
2. Add plugins such as "Allow package downgrade", (something like) "Clean up items that are no longer required", Presto, Repoman etc.
  
Actual results:
  Error message above

Expected results:
  No error message

Additional info: