Check for stable fedup updates before proceeding

[AdamWill]

I've been thinking about how to protect against the F20 fedup 0.7/0.8 issue occurring again. Among other changes, one I thought of is this.

Could fedup, as the first thing it does before proceeding, check whether a newer version of itself is available in the stable updates repository, and recommend/require the user to update to that before proceeding?

This would at least prevent people running into this kind of issue once the 'correct' fedup reached stable.

[hroncok]

Why not even check updates-testing?

[relrod]

I think I agree with @hroncok. Check both and warn the user that it's in testing if it is.

[wgwoods]

There's actually a whole class of problems for which the solution is "install some updates before starting the upgrade" - bug 910326 is another example.

Fixing this class of problems will require:

• Some way to identify which packages should be installed by fedup
• Code in fedup to install those updates (including prompting the user, etc)
• Documentation for maintainers: what to do to mark your package as "required for upgrade"

[AdamWill]

Well, isn't just implementing item #1 on the checklist better than a kick in the teeth? Even if fedup just says 'hey, sport, you should update this stuff before upgrading' and quits, that's better than going ahead and blowing things up. It's doubleplus nice if it actually handles the 'update this stuff' part, but it doesn't really seem required.