Re: [PATCH 2/2] rebase -i: fix SIGSEGV when 'merge <branch>' fails

[Junio C Hamano <gitster@pobox.com>]

Phillip Wood <phillip.wood@talktalk.net> writes:

> This commit implements a minimal fix which fixes the crash and allows
> the user to successfully commit a conflict resolution with 'git rebase
> --continue'. It does not write .git/rebase-merge/patch,
> .git/rebase-merge/stopped-sha or update REBASE_HEAD.

I think that should be OK.  When merging, a patch that shows the
diff from the merge base to the tip indeed is an interesting and
useful reference material to help the conflict resolution, but it is
not even clear what the latter two should mean while merging.

> diff --git a/t/t3430-rebase-merges.sh b/t/t3430-rebase-merges.sh
> index 31fe4268d5..2e767d4f1e 100755
> --- a/t/t3430-rebase-merges.sh
> +++ b/t/t3430-rebase-merges.sh
> @@ -129,7 +129,7 @@ test_expect_success '`reset` refuses to overwrite untracked files' '
>  	git rebase --abort
>  '
>  
> -test_expect_success 'failed `merge` writes patch (may be rescheduled, too)' '
> +test_expect_success 'failed `merge -C` writes patch (may be rescheduled, too)' '
>  	test_when_finished "test_might_fail git rebase --abort" &&
>  	git checkout -b conflicting-merge A &&
>  
> @@ -151,6 +151,19 @@ test_expect_success 'failed `merge` writes patch (may be rescheduled, too)' '
>  	test_path_is_file .git/rebase-merge/patch
>  '
>  
> +SQ="'"

A low-hanging fruit tangent, but somebody may want to go through the
output from

    $ git grep '[Ss][Qq]_*=' t

and come up with a shared "convenience" definition of this, which
perhaps sits next to the definition of $_x40 etc.

> +test_expect_success 'failed `merge <branch>` does not crash' '
> +	test_when_finished "test_might_fail git rebase --abort" &&
> +	git checkout conflicting-G &&
> +
> +	echo "merge G" >script-from-scratch &&
> +	test_config sequence.editor \""$PWD"/replace-editor.sh\" &&
> +	test_tick &&
> +	test_must_fail git rebase -ir HEAD &&
> +	! grep "^merge G$" .git/rebase-merge/git-rebase-todo &&
> +	grep "^Merge branch ${SQ}G${SQ}$" .git/rebase-merge/message
> +'
> +
>  test_expect_success 'with a branch tip that was cherry-picked already' '
>  	git checkout -b already-upstream master &&
>  	base="$(git rev-parse --verify HEAD)" &&