Re: [PATCH v2 3/3] fetch: use bundle URIs when having creationToken heuristic

> At the moment, bundle URIs are only used by git-clone(1). For a clone
> the use of bundle URI is trivial, because the repository is empty so
> downloading bundles will never result in downloading objects that are in
> the repository already.
>
> For git-fetch(1), this more complicated to use bundle URI. We want to

> avoid downloading bundles that only contains objects that are in the
> local repository already.
>
> One way to achieve this is possible when the "creationToken" heuristic
> is used for bundle URIs. We attempt to download and unbundle the minimum

> number of bundles by creationToken in decreasing order. If we fail to
> unbundle (after a successful download) then move to the next
> non-downloaded bundle and attempt downloading. Once we succeed in
> applying a bundle, move to the previous unapplied bundle and attempt to
> unbundle it again. At the end the highest applied creationToken is
> written to `fetch.bundleCreationToken` in the git-config. The next time
> bundles are advertised by the server, bundles with a lower creationToken
> value are ignored. This was already implemented by
> 7903efb717 (bundle-uri: download in creationToken order, 2023-01-31) in
> fetch_bundles_by_token().
>
> Using the creationToken heuristic is optional, but without it the client
> has no idea which bundles are new, how to sort them, and which only have
> objects the client already has.
>
> With this knowledge, make git-fetch(1) use bundle URIs from the server,
> but only when the creationToken heuristic is used.
>