Description of problem:
With yum-langpacks installed and yum plugins enabled, yumex aborts 

Version-Release number of selected component (if applicable):
yum-langpacks-0.3.0-1.fc18.noarch
yum-3.4.3-30.fc18.noarch
yumex-3.0.6-1.fc18.noarch


How reproducible: 100%


Steps to Reproduce:
1. install yum-langpacks
2. run yumex with yum plugins enabled in Preferences->Yum
3.
  
Actual results:
17:57:52 : network connection state check is disabled
17:57:52 : Starting yum child process
17:57:57 : YUM: Yum Version : 3.4.3
17:57:57 : YUM: Loaded plugins: langpacks, presto
17:57:57 : YUM: No plugin match for: refresh-packagekit
17:57:57 : YUM: Traceback (most recent call last):
17:57:57 : YUM:   File "/usr/share/yumex/yum_childtask.py", line 66, in <module>
17:57:57 : YUM:     my = YumServer(debuglevel, plugins, offline, repos, yum_conf)
17:57:57 : YUM:   File "/usr/lib/python2.7/site-packages/yumexbackend/yum_server.py", line 188, in __init__
17:57:57 : YUM:     self.doLock()
17:57:57 : YUM:   File "/usr/lib/python2.7/site-packages/yumexbackend/yum_server.py", line 261, in doLock
17:57:57 : YUM:     yum.YumBase.doLock(self)
17:57:57 : YUM:   File "/usr/lib/python2.7/site-packages/yum/__init__.py", line 1960, in doLock
17:57:57 : YUM:     if self.conf.uid != 0:
17:57:57 : YUM:   File "/usr/lib/python2.7/site-packages/yum/__init__.py", line 1014, in <lambda>
17:57:57 : YUM:     conf = property(fget=lambda self: self._getConfig(),
17:57:57 : YUM:   File "/usr/lib/python2.7/site-packages/yum/__init__.py", line 372, in _getConfig
17:57:57 : YUM:     startupconf.pluginconfpath,disabled_plugins,enabled_plugins)
17:57:57 : YUM:   File "/usr/lib/python2.7/site-packages/yum/__init__.py", line 619, in doPluginSetup
17:57:57 : YUM:     plugin_types, confpath, disabled_plugins, enabled_plugins)
17:57:57 : YUM:   File "/usr/lib/python2.7/site-packages/yum/plugins.py", line 165, in __init__
17:57:57 : YUM:     self.run('config')
17:57:57 : YUM:   File "/usr/lib/python2.7/site-packages/yum/plugins.py", line 187, in run
17:57:57 : YUM:     func(conduitcls(self, self.base, conf, **kwargs))
17:57:57 : YUM:   File "/usr/lib/yum-plugins/langpacks.py", line 133, in config_hook
17:57:57 : YUM:     conduit.registerCommand(LanginstallCommand())
17:57:57 : YUM:   File "/usr/lib/python2.7/site-packages/yum/plugins.py", line 553, in registerCommand
17:57:57 : YUM:     raise Errors.ConfigError(_('registration of commands not supported'))
17:57:57 : YUM: yum.Errors.ConfigError: registration of commands not supported
17:59:55 : Using config file : /home/a/.config/yumex/yumex.conf
17:59:55 : Using config file : /home/a/.config/yumex/yumex.conf



Expected results:
Yumex just works

Additional info:
Modifying /usr/lib/python2.7/site-packages/yum/plugins.py to display the command
generating the error instead of aborting gives the following:
17:51:11 : Starting yum child process
17:51:11 : Using the following repositories :
rpmfusion-nonfree-updates-testing,rpmfusion-free-updates-testing,updates-testing,fedora,rpmfusion-free-rawhide,rpmfusion-nonfree-rawhide,rpm-sphere,updates

17:51:12 : YUM: Yum Version : 3.4.3
17:51:12 : YUM: Loaded plugins: langpacks, presto
17:51:12 : YUM: No plugin match for: refresh-packagekit
17:51:12 : YUM: Crap: Error trying to register  <langpacks.LanginstallCommand instance at 0x2e9d488>
17:51:12 : YUM: Crap: Error trying to register  <langpacks.LangremoveCommand instance at 0x2e9d488>
17:51:12 : YUM: Crap: Error trying to register  <langpacks.LanglistCommand instance at 0x2e9d488>


Also, removing yum-langpacks and/or de-selecting use of yum plugins resolves the issue