Lets try this, it looks like your MWG is still looking for 7.1.5 updates...
rpm -qa|grep mwg #(post the output of this command)
If it shows the 'yumconf' package for an old version, lets remove it:
yum remove yumconf-7.1.5-mwg
yum remove yumconf-7.1.6-mwg
Then when you do the upgrade again, follow the release notes (as I'm sure you did ):
Here is the commands to summarize (do one at a time):
yum clean all
yum remove yumconf-beta
yum install yumconf-7.2.0-mwg
yum upgrade yum yumconf\*
BTW, open a support case if you havent already.
Hope this helps,
It's all working now