Description of problem:
package-cleanup --problems
does not work. It fail with an exception.

Version-Release number of selected component (if applicable):
yum-3.0.6-1.fc6
yum-utils-1.0.3-1.fc6

How reproducible: Always

Steps to Reproduce:
1. package-cleanup --problems
  
Actual results:
Setting up yum
Reading local RPM database
Processing all local requires
Traceback (most recent call last):
  File "/usr/bin/package-cleanup", line 402, in ?
    main()
  File "/usr/bin/package-cleanup", line 399, in main
    provsomething = buildProviderList(my,pkgs,opts.problems)
  File "/usr/bin/package-cleanup", line 85, in buildProviderList
    resolve_sack = my.rpmdb.whatProvides(req,rflags,ver)
  File "/usr/lib/python2.4/site-packages/yum/rpmsack.py", line 390, in whatProvides
    pkgs = self.searchProvides(name)
  File "/usr/lib/python2.4/site-packages/yum/rpmsack.py", line 141, in
searchProvides
    return self.searchPrco(name, 'provides')
  File "/usr/lib/python2.4/site-packages/yum/rpmsack.py", line 123, in searchPrco
    if not result.has_key(po.pkgid):
TypeError: list objects are unhashable