Re: [PATCH v2 11/19] pack-objects: use bitmaps when packing objects

> I think there are two cases that we need to consider:
>
>   1. We have a full repo and somebody requests a shallow clone for us.
>      We probably do not want to use bitmaps here.  In the series we have
>      been testing, shallow clones turned off bitmaps because we do not
>      use the internal rev_list. But as of cdab485 (upload-pack: delegate
>      rev walking in shallow fetch to pack-objects), that distinction
>      doesn't hold. I think we can check the use of --shallow-file
>      instead of explicitly turning off bitmaps there.

>   2. We have a shallow clone that wants to repack. We probably want to
>      turn off bitmap writing here. I don't think that grafts actually
>      matter here, because pack-objects should always be looking at the
>      true graph. It would mean that using "git rev-list
>      --use-bitmap-index" does not respect the grafts, and we should
>      probably disable it in that case (and ditto for replacements).