Sounds reasonable.

Before a push, I'll have the update system toss the rpms in a testclosure repo,
run createrepo on it, then run `repoclosure -n -r testclosure -r core -r
{updates,updates-testing}`, correct ?

To make this possible, I would have to modify repoclosure to use return values
to actually know if there are broken deps or not.

Once they are found, what should the update system do, just halt the push ?

It should probably at least require an override to know that you're pushing
something that may be broken.  Given that multiple updates could be required for
a set, unless the pushing happens as a batch, an override is going to be needed.

There is now a 'Check Dependecies' button next to the 'Push' button in
fedora-updates/push.py.  It seems to be working OK (although I think a
yum{,-util} upgrade on porkchop might speed things up a bit).  I'll work with
Jesse on polishing this feature up.