root@localhost ~ % yum update -y
Traceback (most recent call last):
  File "/usr/bin/yum", line 29, in ?
    yummain.main(sys.argv[1:])
  File "/usr/share/yum-cli/yummain.py", line 85, in main
    base.getOptionsConfig(args)
  File "/usr/share/yum-cli/cli.py", line 183, in getOptionsConfig
    errorlevel=opts.errorlevel)
  File "/usr/lib/python2.4/site-packages/yum/__init__.py", line 123, in
doConfigSetup
    startupconf.pluginconfpath)
  File "/usr/lib/python2.4/site-packages/yum/__init__.py", line 227, in
doPluginSetup
    plugin_types, confpath)
  File "/usr/lib/python2.4/site-packages/yum/plugins.py", line 128, in __init__
    self._importplugins(types)
  File "/usr/lib/python2.4/site-packages/yum/plugins.py", line 169, in
_importplugins
    self._loadplugin(modulefile, types)
  File "/usr/lib/python2.4/site-packages/yum/plugins.py", line 185, in _loadplugin
    module = imp.load_module(modname, fp, pathname, description)
  File "/usr/lib/yum-plugins/installonlyn.py", line 23, in ?
    from yum.packages import YumInstalledPackage, comparePoEVR
ImportError: cannot import name comparePoEVR

root@localhost ~ % rpm -q yum
yum-2.9.5-3