Comment # 3 on bug 1086343 from James Carter

Your guess is very likely correct, that I have repo priorities set in such a
way that a repo with a lower priority number (more preferred) had a
back-version instance of libglib.  I wanted to prove this, but ended up in a
tangle, so I'm just confirming without proof.  

Do you have a recommendation for my use case?  I have an enterprise mirror, and
a procedure to update it overnight and make a report of what packages are going
to be updated, with their changelogs, so I can head off conflicts, e.g. update
the webserver first, rather than when the other hosts are trying to use it to
get packages from the enterprise mirror.  

So is there a standard way to prefer the enterprise mirror when the package
versions are identical, but to prefer the SuSE repo if a new version sneaks in
after the enterprise mirror is updated, which has happened several times?  

In response to the libglib mess, I tried replacing the enterprise mirror with a
Squid proxy with more than enough cache space to hold every installed package. 
This method looks promising but has its own little issues...