yum, rhn-profile-sync, and rhn_check fail with python traceback and error: 'ExpatError: mismatched tag: line <X>, column <Y>'

Issue

• yum commands, rhn-profile-sync, and rhn_check are failing with an error like the following:

xmlrpclib.py:601:feed:ExpatError: mismatched tag: line 14, column 2
Traceback (most recent call last):
  File "/usr/bin/yum", line 29, in <module>
    yummain.user_main(sys.argv[1:], exit_code=True)
  File "/usr/share/yum-cli/yummain.py", line 276, in user_main
    errcode = main(args)
  File "/usr/share/yum-cli/yummain.py", line 98, in main
    base.getOptionsConfig(args)
  File "/usr/share/yum-cli/cli.py", line 228, in getOptionsConfig
    self.conf
  File "/usr/lib/python2.6/site-packages/yum/__init__.py", line 887, in <lambda>
    conf = property(fget=lambda self: self._getConfig(),
  File "/usr/lib/python2.6/site-packages/yum/__init__.py", line 358, in _getConfig
    self.plugins.run('init')
  File "/usr/lib/python2.6/site-packages/yum/plugins.py", line 184, in run
    func(conduitcls(self, self.base, conf, **kwargs))
  File "/usr/share/yum-plugins/rhnplugin.py", line 114, in init_hook
    login_info = up2dateAuth.getLoginInfo()
  File "/usr/share/rhn/up2date_client/up2dateAuth.py", line 219, in getLoginInfo
    login()
  File "/usr/share/rhn/up2date_client/up2dateAuth.py", line 186, in login
    li = server.up2date.login(systemId)
  File "/usr/share/rhn/up2date_client/rhnserver.py", line 50, in __call__
    return rpcServer.doCall(method, *args, **kwargs)
  File "/usr/share/rhn/up2date_client/rpcServer.py", line 206, in doCall
    ret = method(*args, **kwargs)
  File "/usr/lib64/python2.6/xmlrpclib.py", line 1199, in __call__
    return self.__send(self.__name, args)
  File "/usr/share/rhn/up2date_client/rpcServer.py", line 39, in _request1
    ret = self._request(methodname, params)
  File "/usr/lib/python2.6/site-packages/rhn/rpclib.py", line 383, in _request
    self._handler, request, verbose=self._verbose)
  File "/usr/lib/python2.6/site-packages/rhn/transports.py", line 188, in request
    return self._process_response(fd, connection)
  File "/usr/lib/python2.6/site-packages/rhn/transports.py", line 216, in _process_response
    return self.parse_response(fd)
  File "/usr/lib/python2.6/site-packages/rhn/transports.py", line 236, in parse_response
    p.feed(response)
  File "/usr/lib64/python2.6/xmlrpclib.py", line 601, in feed
    self._parser.Parse(data, 0)
ExpatError: mismatched tag: line 14, column 2