pull: Only fetch all refs if we're mirroring
pull: Only fetch all refs if we're mirroring

I noticed xdg-app was looping trying to fetch 1427 refs.  We
don't want to do that unless asked to.

(And also, we need to make static delta requests async)

leandrosansilva/ostree,leandrosansilva/ostree,gatispaeglis/ostree,GNOME/ostree,gatispaeglis/ostree,leandrosansilva/ostree,gatispaeglis/ostree,gatispaeglis/ostree,GNOME/ostree,GNOME/ostree,leandrosansilva/ostree,gatispaeglis/ostree,gatispaeglis/ostree,leandrosansilva/ostree,GNOME/ostree,GNOME/ostree