Description of problem:
the yum-priorities plugin no longer excludes obsoletes due to a change in yum's
obsoletes dictionary format.

Version-Release number of selected component (if applicable):
yum-priorities-1.1.5-1.fc7

How reproducible:
Always

Steps to Reproduce:
1. yum install yum-priorities
2. add "check_obsoletes=1" to /etc/yum/pluginconf.d/priorities.conf
3. add "priority=1" to /etc/yum.repos.d/fedora*.repo:
perl -i -pe "s/(^\s*\[.*\])/\1\npriority=1/" /tmp/yum.repos.d/{fedora*,livna*}
4. add the nasty ATRPMS 3rd party repository.  # default priority is 99
5. yum --enablerepo=atrpms update     

Actual results:
ATRPMS is still allowed to obsolete packages in the protected priority=1 repo.
At the time of this bugreport, on my system, the two packages being overridden
are "PIL" obsoleting "python-imaging", and "mpg123" replacing "mpg321".

Expected results:
obsoletes excluded.

Additional info:
The plugin author - Daniel de Kok - writes: """this bug seems to be introduced
by a change by the yum-utils maintainers. They changed the code to use the
second element in an obsolete tuple to get the architecture, while this element
clearly does not list the arch, and I don't think it ever did."""

An example obsoletes dict entry:
(u'PIL', u'i386', u'0', u'1.1.6', u'8.fc7'): [   (   u'python-imaging',
                                                          u'LT',
                                                          (   u'0',
                                                              u'1.1.6',
                                                              u'8.fc7'))],

I've tested the original version of this plugin --
http://devel.linux.duke.edu/cgi-bin/viewcvs.cgi/yum-utils/plugins/priorities/priorities.py?revision=1.1
-- and it correctly filters out the obsoletes.

Diffing yum-priorities-1.1.5-1.fc7 against the working version shows:

81,82c81
<                 key = "%s.%s" % (po.name,po.arch)
<                 if pkg_priorities.has_key(key) and pkg_priorities[key] <
repo.priority:
---
>                 if pkg_priorities.has_key(po.name) and pkg_priorities[po.name]
< repo.priority:
91,92c90
<                             key = "%s.%s" % (obsolete_pkg[0],obsolete_pkg[1])
<                             if pkg_priorities.has_key(key) and
pkg_priorities[key] < repo.priority:
---
>                             if pkg_priorities.has_key(obsolete_pkg[0]) and
pkg_priorities[obsolete_pkg[0]] < repo.priority:
102,103c100
<         key = "%s.%s" % (p.name,p.arch)
<         out[key] = priority
---
>         out[p.name] = priority