Bug 448470

Description of problem:
When attempting to configure yum to access the internet via a proxy,
by setting the variables (in accordance with the limited documentation in man
yum.conf and 
http://docs.fedoraproject.org/yum/sn-yum-proxy-server.html)
in the /etc/yum.conf file, 

proxy=http://proxy.server:port
proxy_username=username
proxy_password=password

I get a confusing error message:

[root@tacat etc]# yum update
Loading "changelog" plugin
Loading "installonlyn" plugin
Loading "security" plugin
Loading "rhnplugin" plugin
Loading "protectbase" plugin
Setting up Update Process
Setting up repositories
Could not retrieve mirrorlist http://apt.sw.be/redhat/el5/en/mirrors-rpmforge
error was
[Errno 4] IOError: <urlopen error nonnumeric port: '8080?'>
Error: Cannot find a valid baseurl for repo: rpmforge

To make the error message go away, simply append a '/' to the end of the proxy
setting. However, the '/' is not shown in any documentation.

Version-Release number of selected component (if applicable):
yum-3.0.1-5.el5

How reproducible:
Always

Steps to Reproduce:
1. Configure yum.conf as described above, with no '/' on the end of the proxy
setting.
2. yum update
  
Actual results:
[Errno 4] IOError: <urlopen error nonnumeric port: '8080?'>


Expected results:
successful update

Additional info:
If this is the correct behaviour, please update the documentation.
Otherwise, fix it to correctly parse the port number!