Description of problem:
Setting baseurl to something like this:
baseurl=file:///media/Fedora 7 i386 DVD
and using yum results in error.

Version-Release number of selected component (if applicable):
yum-3.2.0-1.fc7

How reproducible:
Always

Steps to Reproduce:
1. Default-mount installation DVD to /media/Fedora 7 i386 DVD
2. Add this path to any repo config as baseurl
3. Try yum install whatever
  
Actual results:

# yum install kdebase
Loading "installonlyn" plugin
Options Error: Error parsing 'file:///media/Fedora 7 i386 DVD': URL must be
http, ftp, file or https not ""


Expected results:
'not ""' is misleading when yum itself says this message.
Yum should either accept at least shell escape space or convert spaces to %20.

Additional info:
Workaround is to put in the path %20 instead of spaces.