From: D. Ben Knoble <ben.knoble@gmail.com>
Date: Wed, 29 Apr 2026 13:16:00 GMT
Subject: Re: [Bug] fetch --deepen truncates history in v2.54.0
Message-ID: <CALnO6CBzd0coeyJ9B+EkGWsSNEVTdVLvcVmEraGNxnUm5wXy=g@mail.gmail.com>
In-Reply-To: <CANOh7gEEw+6146NN3JV8EYxQarj0KkyA7r3RZ6v-DxeqQZLrCA@mail.gmail.com>

On Wed, Apr 29, 2026 at 7:27 AM Owen Stephens <owen@owenstephens.co.uk> wrote:
>
> > What did you do before the bug happened? (Steps to reproduce your issue)
>
> Repeatedy called `git fetch --deepen 2` inside a shallow repo that was a
> file:// clone of another repo. Once all commits had been fetched, a subsequent
> `fetch --deepen` appears to "reset" the repo back to being shallow with a depth
> of 2. A reproduction script is included below. This issue appears to have been
> introduced in v2.54.0.
>
> > What did you expect to happen? (Expected behavior)
>
> I expected `git fetch --deepen` in a non-shallow repo with no upstream commits
> to be a no-op.

Here's the relevant part of git-fetch(1):

       --depth=<depth>
           Limit fetching to the specified number of commits from the tip of
           each remote branch history. If fetching to a shallow repository
           created by git clone with --depth=<depth> option (see git-clone(1)),
           deepen or shorten the history to the specified number of commits.
           Tags for the deepened commits are not fetched.

       --deepen=<depth>
           Similar to --depth, except it specifies the number of commits from
           the current shallow boundary instead of from the tip of each remote
           branch history.

I can see how one might read this as implying that when fetching in a
non-shallow repository, there's no effect, but I don't think the text
explicitly says that. In fact, the first sentence under "--depth"
(which is of course relevant for "--deepen") is unconditional.

So I'm not sure it should be a no-op.

That said, it is possible the behavior changed between 2.53 and 2.54?
I haven't tried to reproduce or bisect yet.

Best,
D. Ben Knoble