Description of problem:
* RHN Proxy 5.4.1 in an IPv6 only environment
* System registration via proxy results into an internal server error
* Following error shows in /var/log/httpd/error_log on proxy:

Exception Handler Information
Traceback (most recent call last):
  File "/usr/share/rhn/proxy/apacheServer.py", line 66, in __call__
    ret = f(req)
  File "/usr/share/rhn/proxy/apacheHandler.py", line 341, in handler
    ret = handlerObj.handler()
  File "/usr/share/rhn/proxy/broker/rhnBroker.py", line 206, in handler
    self._connectToParent()  # part 1
  File "/usr/share/rhn/proxy/rhnShared.py", line 137, in _connectToParent
    (self.uri, )))
TypeError: not all arguments converted during string formatting

Version-Release number of selected component (if applicable):
spacewalk-proxy-common-1.2.2-11

How reproducible:
Always

Steps to Reproduce:
1. RHN Proxy in IPv6 only environment
2. System registration via proxy
  
Actual results:
Internal server error, error in httpd/error_log on proxy.

Expected results:
Registration succeeds.

Additional info:
Problem only shows in IPv6 only environment.