Fix repo setup for Branched update tests (I hope)
    
    Branched update tests are all failing because the baseurl in
    fedora.repo is incorrect for Branched. This is a rather hacky
    fix for this problem. It relies on the scheduler setting the
    DEVELOPMENT variable when the update is for Branched (I named
    the variable DEVELOPMENT rather than BRANCHED to be more
    future-proof).
    
    Alternative options I rejected were:
    
    i) stick with MM links
    ii) do something 'clever' to retrieve the URLs from MM
    
    Rejected i) because the timing problem where the infra repo gets
    updated before MM has the updated repodata checksums is just too
    much of a problem; whenever that happens, dnf will refuse to use
    the metadata from the infra repo and go pull it from an external
    mirror, which can wind up timing out.
    
    Rejected ii) because it seemed too fancy and not really any more
    robust than just doing this and adapting it if Things Change In
    Future (TM).