This will eventually replace the remote_location property. The latter
pins a specific location (a specific mirror), but the two former
can together be used to re-resolve to a more suitable mirror at the
time/place the package will actually be downloaded.
Rather than pinning mirrors in the osbuild manifests, we want to be
able to include the metalink and relative locations so each worker
can use mirrors closer to them.
This would be particularly important when pipelines are rebuilt in
the future, and the best mirrors may have changed.
Signed-off-by: Tom Gundersen <teg@jklm.no>
7ea74cd131