Change how we handle refs in child-repo for system installs
Change how we handle refs in child-repo for system installs

We used to to do a MIRROR pull and make a copy of the upstream summary
file in the child repo. However, now that we want to allow side-loading
from a repo with a partial summary we can no longer do that.

So, the new approach is that the child repo *always* contains
"remote:ref" style refs (never heads or mirror/collection-id refs),
but in order to not let you import a signel commit into the wrong ref
name we now require the commits to have a ref-binding (they all do
since a long time anyway).

flatpak/flatpak,flatpak/flatpak,flatpak/flatpak,flatpak/flatpak,flatpak/flatpak