Historically the p2p resolve code always did a parallel call to find
all the available commits for the refs, and then it took the results
and pulled only the commits for all the refs so that it could resolve
against the exact commits that were available (which might not match
with whatever metadata we have in the local ostree-metadata copy.
This splits this into two phases, the first that uses the summary only,
and a second one that pulls the commit.
The reason for this is that we want to be able to do some stuff inbetween
these, such as resolving some refs via the ostree-metadata and maybe
requesting bearer tokens that we need for pulling the commit objects.
5a01ff44d6