Description of problem:
This is an issue fo upstream yum.

When running a K12LTSP-5.0.0beta2 system,
yum install switchdesk
  fails with:
---> Downloading header for switchdesk to pack into transaction set.
http://k12linux.mesd.k12.or.us/K12LTSP/testing/5.0.0-32bit/Fedora/RPMS/switchdesk-4.0.8-4.noarch.rpm:
[Errno 14] HTTP Error 404: Date: Thu, 13 Apr 2006 16:24:16 GMT

Background:
This bug was found when using yum on the 5.0.0beta2 version of K12ltsp.

K12Ltsp integrates the Linux Terminal Server Project with Fedora Core in order
to run thin client computer labs at schools.  The maintainers have modified
fedora Core and produce their own repository that is a combination of vanilla
Fedora Core packages and packages which they have modified or added.  In the
setup where the problem was revealed, the Fedora Core repository is enabled
alongside the K12LTSP repository.  Because of this, there are many packages
which overlap in exact NEVR between the two.

Analysis:
The error generated with yum install switchdesk reveals something interesting:
http://k12linux.mesd.k12.or.us/K12LTSP/testing/5.0.0-32bit/Fedora/RPMS/switchdesk-4.0.8-4.noarch.rpm:

                                                        ^^^^^--- i386 is missing
A bit of research shows that the K12LTSP repository URL is:
  http://k12linux.mesd.k12.or.us/K12LTSP/testing/5.0.0-32bit/
and the switchdesk package <location> tag is
  <location>i386/Fedora/RPMS/switchdesk-4.0.8-4.noarch.rpm</location>

The Fedora Core repo has:
'http://redhat.download.fedoraproject.org/pub/fedora/linux/core/5/i386/os/'
<location href="Fedora/RPMS/switchdesk-4.0.8-4.noarch.rpm"/>

So it appears that yum is comparing packages using NEVR.  It finds two which are
 the same and assumes they are the same in all other respects.  Then yum uses
the location entry from the Fedora Core repo but attempts to pull the package
from the K12LTSP repo.  This leads to the lack of "i386" in the final URL.

Version-Release number of selected component (if applicable):
yum-2.6.0-1

How reproducible:


Steps to Reproduce:
1. Enable the K12LTSP-5.0.0beta2 repository on a Fedora Core 5 machine
2. yum -y erase switchdesk
3. yum -y install switchdesk
  
Actual results:
Package fails to install as detailed above.

Expected results:
Package would install

Additional info:
* Disabling either the Fedora Core or K12LTSP repo allows yum to pull the
package down.
* This does not occur with all packages (for instance, binutils matches the
correct location with the correct repository)
* I noticed that the repodata seems to be in an older format
<location></location> instead of <location href=""/>.  If this is the whole
reason, let me know and I'll just tell K12LTSP to run a newer createrepo on
their repository.