Error Type: <type 'exceptions.AttributeError'>
Error Value: 'NoneType' object has no attribute 'timestamp'
  File : /usr/share/PackageKit/helpers/yum/yumBackend.py, line 2202, in <module>
    main()
  File : /usr/share/PackageKit/helpers/yum/yumBackend.py, line 2199, in main
    backend.dispatcher(sys.argv[1:])
  File : /usr/lib/python2.5/site-packages/packagekit/backend.py, line 599, in dispatcher
    self.dispatch_command(args[0], args[1:])
  File : /usr/lib/python2.5/site-packages/packagekit/backend.py, line 525, in dispatch_command
    self.refresh_cache()
  File : /usr/share/PackageKit/helpers/yum/yumBackend.py, line 1128, in refresh_cache
    self.yumbase.repos.populateSack(which=[repo.id], mdtype='metadata', cacheonly=1)
  File : /usr/lib/python2.5/site-packages/yum/repos.py, line 251, in populateSack
    sack.populate(repo, mdtype, callback, cacheonly)
  File : /usr/lib/python2.5/site-packages/yum/yumRepo.py, line 160, in populate
    if self._check_db_version(repo, mydbtype):
  File : /usr/lib/python2.5/site-packages/yum/yumRepo.py, line 217, in _check_db_version
    return repo._check_db_version(mdtype)
  File : /usr/lib/python2.5/site-packages/yum/yumRepo.py, line 1119, in _check_db_version
    repoXML = self.repoXML
  File : /usr/lib/python2.5/site-packages/yum/yumRepo.py, line 1277, in <lambda>
    repoXML = property(fget=lambda self: self._getRepoXML(),
  File : /usr/lib/python2.5/site-packages/yum/yumRepo.py, line 1269, in _getRepoXML
    self._loadRepoXML(text=self)
  File : /usr/lib/python2.5/site-packages/yum/yumRepo.py, line 1259, in _loadRepoXML
    return self._groupLoadRepoXML(text, ["primary"])
  File : /usr/lib/python2.5/site-packages/yum/yumRepo.py, line 1243, in _groupLoadRepoXML
    if self._commonLoadRepoXML(text):
  File : /usr/lib/python2.5/site-packages/yum/yumRepo.py, line 1112, in _commonLoadRepoXML
    if not self._groupCheckDataMDNewer():
  File : /usr/lib/python2.5/site-packages/yum/yumRepo.py, line 994, in _groupCheckDataMDNewer
    old_repo_XML.timestamp > self.repoXML.timestamp):


people i also got a "Error code: sec_error_unknown_issuer" just when trying to report the bug here on the site (bugs.freedesktop.org) on my Fedora 10 fresh installed system