Description of problem:
If you have a repo containing packages for say both i386 and x86_64, and one
package available for both arches obsoletes another package that is installed
for only one of the arches, then both versions get installed.

Version-Release number of selected component (if applicable):
yum-2.9.3-2
rpm-4.4.2-31

How reproducible:
Every time

Steps to Reproduce:
1.Install random package x.{x86_64,i386,noarch}, doesn't matter
2.Build package y.i386 and y.x86_64, with Obsoletes: x
3.Create a yum repository with the y packages
4.Run yum update

Actual results:
Yum will install both y packages.

Expected results:
It would be nicer if it installed a package for the same arch or, failing that
because there's no such obsoletion package, the package in the arch most
suitable for the local configuration (in the example case, x86_64).

Additional info: