[Yum] yum check

[seth vidal]

> "yum check" is the same as "yum check installed" and would check the 
> installed packages.
> 
> "yum check updates" would check the updates for dependencies.
> 
> "yum check <package>" would check the dependencies for the given package.
> 
> "yum check available" would check the dependencies for installing all 
> the available packages.
> 
> This would be very useful for finding compatibility problems between 
> repositories.  If yum had the concept of the list of packages for an 
> individual repository, it would useful to do "yum check [freshrpms]" and 
> check installing all the freshrpm packages.

So an interesting take would be to iterate over all the deps and
provides and sort them out one for the other, so keep removing deps from
the total list based on a provider until you either 1. had no remaining
deps or 2. had nothing that provided for those deps. In the current .hdr
format it's possible but kinda a pain in the ass. In the new metadata
format I think it will be a lot easier to sort them and kinda a neat
data mining experiment.

As soon as I have yum working with the new metadata format I'll post
some code and people can start tinkering.

I'm really rather excited by the new metadata and so far I'm pleased
with most of the results.

-sv