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References: <pull.9.git.gitgitgadget@gmail.com> <pull.9.v2.git.gitgitgadget@gmail.com>
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From:   Eric Sunshine <sunshine@sunshineco.com>
Date:   Tue, 17 Jul 2018 13:45:03 -0400
Message-ID: <CAPig+cRh5qezsFFkecwM1uVdeCwgTFqFnpUPDmb+GdNFVUUx4g@mail.gmail.com>
Subject: Re: [PATCH v2 2/2] repack -ad: prune the list of shallow commits
To:     gitgitgadget@gmail.com
Cc:     Git List <git@vger.kernel.org>, Junio C Hamano <gitster@pobox.com>,
        Johannes Schindelin <johannes.schindelin@gmx.de>
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On Tue, Jul 17, 2018 at 9:51 AM Johannes Schindelin via GitGitGadget
<gitgitgadget@gmail.com> wrote:
> While it is true that we never add unreachable commits into pack files
> intentionally (as `git repack`'s documentation states), we must not
> forget that a `git fetch --prune` (or even a `git fetch` when a ref was
> force-pushed in the meantime) can make a commit unreachable that was
> reachable before.
>
> Therefore it is not safe to assume that a `git repack -adlf` will keep
> unreachable commits alone (under the assumption that they had not been
> packed in the first place).
>
> This is particularly important to keep in mind when looking at the
> `.git/shallow` file: if any commits listed in that file become
> unreachable, it is not a problem, but if they go missing, it *is* a
> problem. One symptom of this problem is that a deepening fetch may now
> fail with
>
>         fatal: error in object: unshallow <commit-hash>
>
> To avoid this problem, let's prune the shallow list in `git repack` when
> the `-d` option is passed, unless `-A` is passed, too (which would force
> the now-unreachable objects to be turned into loose objects instead of
> being deleted). Additionally, e also need to take `--keep-reachable` and

s/, e/, we/

> `--unpack-unreachable=<date>` into account.
>
> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>