Discard packages from epoch that were not downloaded

Instead of including packages in the epoch map that were
not even downloaded (but were found on epel or elsewhere)
just remove those with an epoch set that were not automatically
downloaded as part of the dependency downloading process.

Change-Id: I7d9be8393d5cbd2a39029b91279cd5229f5b3f11
Merge "Discard packages from epoch that were not downloaded"