From Bugzilla Helper:
User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.8.0.10) Gecko/20070409 CentOS/1.5.0.10-2.el5.centos Firefox/1.5.0.10

Description of problem:
yumex crashes upon setting of a malformed proxy url (e.g.: "localhost:8080"), which is missing the protocol part (http, ftp or https).

* routine: 
BackgroundRunner
* error: 
Error parsing 'localhost:8080': URL must be http, ftp or https not "localhost"
* dump:
Component: yumex
Version: 1.2.2
Summary: TB03120a34 yumexmain.py:1045:_runBackground:ValueError: Error parsing 'localhost:8080': URL must be http, ftp or https not "localhost"

Traceback (most recent call last):
  File "/usr/share/yumex/yumexmain.py", line 231, in on_repoRefresh_clicked
    self.setup_yum()
  File "/usr/share/yumex/yumexmain.py", line 989, in setup_yum
    if self._runBackground( self.yumexbase.setup, rload ):
  File "/usr/share/yumex/yumexmain.py", line 1045, in _runBackground
    raise self.backgroundThread.exception
ValueError: Error parsing 'localhost:8080': URL must be http, ftp or https not "localhost"

Local variables in innermost frame:
runfunc: <bound method yumexBase.setup of <yumex.yumexBase.yumexBase object at 0x19fb3750>>
args: (False,)
self: <__main__.YumexMainApplication instance at 0x19fa4b90>

*end dump


Version-Release number of selected component (if applicable):
yumex-1.2.2-1.0

How reproducible:
Always


Steps to Reproduce:
1. insert the proxy url
2. update 
3. watch it blow

Actual Results:
crash.

Expected Results:
use the given proxy (? maybe have a default protocol setting ?).

Additional info:
If the DNS resolver would have worked right instead of using 1.0.0.0 on IPv6 responses, I wouldn't have used a proxy.
Tell the DNS resolver guys to do you a favour, and resove using IPv4 as default, or at least provide a system-wide (effective!) configuration to disable IPv6.
It was easier to setup a proxy then deal with the IPv6.
And as you see, it wasn't too easy... :)