Problem with packagesource::sites in setup

[Ken Brown]

I think we're currently mishandling packagesource::sites when several 
libsolv repos contain the same version of a package.  If I'm not 
mistaken, we create a new packageversion pv for each repo, and 
pv.source()->sites contains a single site, corresponding to that repo.

So we never take advantage of the fact that we have more than one mirror 
(or mirror directory) from which we can potentially obtain an archive 
for the package.

I think the way to fix this is to consolidate all the packageversions pv 
into a single one, which knows about all the sites.

This could be handled by packagemeta::add_version().  When it replaces 
an existing version, it could remove the old one from the pool after 
copying the sites information.  In order to obtain the sites 
information, it would have to be able to query the libsolv pool, so we 
would have to internalize repo data as we go along, presumably in the 
IniDBBuilderPackage destructor.

Does this sound about right?  If so, I'll try to prepare a patch.  Or 
maybe there's a better/easier way to solve the problem.

Ken