Description of problem:
This problem revealed when QE was testing availability and updateability of
lvm2 from RHN. The new lvm2 requires a newer device-mapper, but yum pulled
down only the native version. Transaction test then failed because the old
compat-arch package was still installed, which created a conflict. It happened
on all multilib arches (i386 passed), attached is a log from an x86_64 box.

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

How reproducible:
Always

Steps to Reproduce:
See the attachment for inspiration.
  
Actual results:
Transaction test failure, yum exits.

Expected results:
Yum should pull down both rpms (for both arches), the transaction would pass.

Additional info:
Good thing 'yum update' is able to update both device-mapper packages, so this
is nothing that would block full upgrade.