How are i386 packages selected for x86_64 repos?

[Bruno Wolff III]

On Fri, Sep 19, 2008 at 11:07:04 -0500,
  Bruno Wolff III <bruno at wolff.to> wrote:
> I was thinking of trying the same thing with x86_64 but I don't think I want
> to pull in all of the i386 packages and was wondering how the list of i386
> packages was selected for normal x86_64 repos?

I thought about this issue for a bit and I think the answer is to include
all i386, i686 packages that provide something that is not provided by
any x86_64 package. Previously I was looking for some way to flag i386
specific stuff, but that was thinking too narrowly.
I am not sure of the best way to do the above, but I think I will be able to
get something to work. I'll also need to be a little careful of version
differences as my i386 and x86_64 rpms may have a couple of packages out
of sync because of checking koji at different times. That should be a solveable
problem as well.