Conflict with old fedpkg
    
    There is the realms attribute for Commands class that is not accepted by
    fedpkg older than 1.26 (the latest build at this point). This patch will
    prevent people using Fedora Rawhide from installing new pyrpkg without
    upgrading fedpkg as well.
    
    Bug: https://bugzilla.redhat.com/show_bug.cgi?id=1402882
    Signed-off-by: Lubomír Sedlář <lsedlar@redhat.com>