Re: git rebase: retain original head?

[Johannes Schindelin <Johannes.Schindelin@gmx.de>]

Hi Nazri,

On Wed, 27 Feb 2019, Nazri Ramliy wrote:

> On Wed, Jan 9, 2019 at 10:08 PM Johannes Schindelin
> <Johannes.Schindelin@gmx.de> wrote:

Oh wow. Better late than never, eh?

> > Having said that, it is an unintended regression in the built-in
> > rebase. Markus, could you come up with a minimal test case, preferably
> > in the form of a patch to t/t3415-rebase-autosquash.sh?
> 
> Something like this, perhaps? ("gmail converts tabs to spaces" caveat
> applies to the diff formatting):
> 
> --8<--
> diff --git t/t3400-rebase.sh t/t3400-rebase.sh
> index 3e73f7584c..cb55597a8b 100755
> --- t/t3400-rebase.sh
> +++ t/t3400-rebase.sh
> @@ -59,6 +59,13 @@ test_expect_success 'rebase against master' '
>   git rebase master
>  '
> 
> +test_expect_success 'rebase sets ORIG_HEAD' '
> + echo Add B. > expect &&
> + echo Modify A. >> expect &&
> + git log --oneline --format=%s ORIG_HEAD.. > actual &&
> + test_cmp expect actual
> +'
> +
>  test_expect_success 'rebase, with <onto> and <upstream> specified as
> :/quuxery' '
>   test_when_finished "git branch -D torebase" &&
>   git checkout -b torebase my-topic-branch^ &&
> -->8--

I made it a little more stand-alone, and can confirm that this is now
safely a regression in v2.21.0.

> Bisect shows that the first bad commit is this one:
> 
> commit 21853626eac565dd42572d90724b29863f61eb3b
> Author: Johannes Schindelin <johannes.schindelin@gmx.de>
> Date:   Fri Jan 18 07:09:27 2019 -0800
> 
>     built-in rebase: call `git am` directly
> 
> I verified that by undoing the crux of that commit, and that fixes the
> failing test:
> 
> -->8--
> diff --git builtin/rebase.c builtin/rebase.c
> index 7c7bc13e91..848f6740a0 100644
> --- builtin/rebase.c
> +++ builtin/rebase.c
> @@ -728,11 +728,6 @@ static int run_specific_rebase(struct rebase_options *opts)
>   goto finished_rebase;
>   }
> 
> - if (opts->type == REBASE_AM) {
> - status = run_am(opts);
> - goto finished_rebase;
> - }
> -
>   add_var(&script_snippet, "GIT_DIR", absolute_path(get_git_dir()));
>   add_var(&script_snippet, "state_dir", opts->state_dir);
> 
> --8<--
> 
> But something seems off by my bisection in that the "bad" commit
> happens about 10 days after this email thread :/

Yep, I had fixed the issue before this commit, and a regression test would
have come in handy to prevent that regression from creeping in *again*.

Anyway, I'm on it.
Johannes

P.S.: If you want to follow my progress, I'll push updates to the
rebase-am-and-orig-head branch at https://github.com/dscho/git.