Subject: Re: [Bug] fetch --deepen truncates history in v2.54.0

From: René Scharfe <[email-masked]>
Date: Tue, 5 May 2026 22:34:37 +0200

On 5/5/26 9:27 PM, Samo Pogačnik wrote:
> 
> Hi, thanks for pointing out this edge case. Would you care to check the
> following change (the provided test is also a bit modified):

There's spurious wrapping in the patch, but the changes look good to me.

Care to send them with a commit message and sign-off?

René

> diff --git a/shallow.c b/shallow.c
> index a156006d88..ec95653132 100644
> --- a/shallow.c
> +++ b/shallow.c
> @@ -245,7 +245,11 @@ struct commit_list *get_shallow_commits(struct object_array
> *heads,
>                                         int depth, int shallow_flag, int
> not_shallow_flag)
>  {
>         if (shallows && deepen_relative) {
> -               depth += get_shallows_depth(heads, shallows);
> +               int cur_shallow_depth = get_shallows_depth(heads, shallows);
> +               if (cur_shallow_depth)
> +                       depth += cur_shallow_depth;
> +               else
> +                       return NULL;

Nice.  get_shallows_depth() returns 0 on full clones; translating it to
an empty list of shallow commits makes sense.

>         }
>         return get_shallows_or_depth(heads, NULL, NULL,
>                                      depth, shallow_flag, not_shallow_flag);
> diff --git a/t/t5537-fetch-shallow.sh b/t/t5537-fetch-shallow.sh
> index 6588ce6226..9982dd2aa6 100755
> --- a/t/t5537-fetch-shallow.sh
> +++ b/t/t5537-fetch-shallow.sh
> @@ -251,6 +251,16 @@ test_expect_success '.git/shallow is edited by repack' '
>                 origin "+refs/heads/*:refs/remotes/origin/*"
>  '
>  
> +test_expect_success 'fetch --deepen does not truncate' '
> +       git clone --no-local .git full-clone &&
> +       git -C full-clone rev-parse --is-shallow-repository >expect &&
> +       git -C full-clone log --oneline >>expect &&
> +       git -C full-clone fetch --deepen=1 &&
> +       git -C full-clone rev-parse --is-shallow-repository >actual &&
> +       git -C full-clone log --oneline >>actual &&

Using the exact same commands to prepare expect and actual creates a
pleasant symmetry.

> +       test_cmp expect actual
> +'
> +
>  . "$TEST_DIRECTORY"/lib-httpd.sh
>  start_httpd
>