peer: dissolve `_peerlookup` into its last two callers This is about to need more changes and the function won't be useful. We do it early to clarify later changes.

peer: stop having a `peer()` method on `peer()` This is already a peer, why do you want a peer if you already have one.

clone: explicitly detect the need to fetch a peer Instead of having `peer()` method on all `peer()` for this usecase, we could simply handle it explicitly.

addbranchrevs: explicitly detect the need to fetch a peer Instead of having `peer()` method on all `peer()` for this usecase, we could simply handle it explicitly.