yum error: TypeError: 'NoneType' object is not callable

Issue

• yum コマンドに失敗し、以下のトレースバックが表示されます。

# yum update
Loaded plugins: rhnplugin, security
Traceback (most recent call last):
  File "/usr/bin/yum", line 29, in ?
    yummain.user_main(sys.argv[1:], exit_code=True)
  File "/usr/share/yum-cli/yummain.py", line 309, in user_main
    errcode = main(args)
  File "/usr/share/yum-cli/yummain.py", line 161, in main
    return exFatal(e)
  File "/usr/share/yum-cli/yummain.py", line 64, in exFatal
    logger.critical('\n\n%s', to_unicode(e))
  File "/usr/lib64/python2.4/logging/__init__.py", line 1019, in critical
    apply(self._log, (CRITICAL, msg, args), kwargs)
  File "/usr/lib64/python2.4/logging/__init__.py", line 1078, in _log
    record = self.makeRecord(self.name, level, fn, lno, msg, args, exc_info)
  File "/usr/lib64/python2.4/logging/__init__.py", line 1064, in makeRecord
    return LogRecord(name, level, fn, lno, msg, args, exc_info)
  File "/usr/lib64/python2.4/logging/__init__.py", line 226, in __init__
    if args and (len(args) == 1) and args[0] and (type(args[0]) == types.DictType):
TypeError:'NoneType' object is not callable

• rhn_register を実行してシステムを再登録しましたが失敗し、以下のメッセージが表示されます。

An error has occurred:              
Network error:                      
See /var/log/up2date for more information

• /var/log/update ログファイルに、以下のエラーメッセージが表示されます。

Traceback (most recent call last):
  File "/usr/sbin/rhn_register", line 82, in ?
    app.run()
  File "/usr/share/rhn/up2date_client/rhncli.py", line 66, in run
    sys.exit(self.main() or 0)
  File "/usr/sbin/rhn_register", line 64, in main
    ui.main()
  File "/usr/share/rhn/up2date_client/tui.py", line 1753, in main
    tui.run()
  File "/usr/share/rhn/up2date_client/tui.py", line 1645, in run
    result = win.run()
  File "/usr/share/rhn/up2date_client/tui.py", line 127, in run
    tui_call_wrapper(self.screen, rhnreg.getCaps)
  File "/usr/share/rhn/up2date_client/tui.py", line 66, in tui_call_wrapper
    results = func(*params)
  File "/usr/share/rhn/up2date_client/rhnreg.py", line 295, in getCaps
    s.capabilities.validate()
  File "/usr/share/rhn/up2date_client/rhnserver.py", line 159, in __get_capabilities
    self.registration.welcome_message()
  File "/usr/share/rhn/up2date_client/rhnserver.py", line 69, in __call__
    raise up2dateErrors.NetworkError(message)
up2date_client.up2dateErrors.NetworkError:Network error