Re: `BUG: sequencer.c:921: GIT_AUTHOR_DATE missing from author script` when trying to reword in interactive rebase

From: Jeff King <peff@peff.net>
Date: Nov 2, 2021, 01:27 UTC
Message-ID: <YYCT7tLfphH049h+@coredump.intra.peff.net>
In-Reply-To: <000201d7cf76$a4861460$ed923d20$@ruhr-uni-bochum.de>

On Tue, Nov 02, 2021 at 12:17:29AM +0100, Jonas Kittner wrote:

> In the interactive prompt I changed `pick` to `reword`, saved and closed the
> prompt.
> Commands to repoduce see below

Thanks for the easy reproduction. Here are commands that slightly simplify / automate things, which I used to bisect:

  rm -rf repo
  git init repo
  cd repo
  git commit --allow-empty -qm base

  touch file
  git add .
  GIT_AUTHOR_DATE='@123456789 +0000' git commit -qm "this message says pick"

  GIT_EDITOR='sed -i s/pick/reword/' \
  git.compile rebase -i --committer-date-is-author-date HEAD^

  # not strictly necessary, but when it works, you can see that the
  # timestamps correctly match, and that "pick" was changed to "reword"
  # in the message. Of course when it doesn't work, rebase aborts, so
  # that's easier to see than looking at the commit. :)
  git cat-file commit HEAD

Show 9 quoted lines

> What happened instead? (Actual behavior)
> segfault: `BUG: sequencer.c:921: GIT_AUTHOR_DATE missing from author script`
>
> [...]
>
> https://github.com/git/git/commit/7573cec52c0274ceb166c425be4288f6b3103d6f#d
> iff-0e574dc9087fc7831bbc1403545a8561f08869576c1ccc4146aa276146ff9777R888-R88
> 9
> this seems to be not the case and needs to be handled differently I guess?

It looks like things did work back in 7573cec52c (rebase -i: support --committer-date-is-author-date, 2020-08-17). Bisecting shows that it broke in baf8ec8d3a (rebase -r: don't write .git/MERGE_MSG when fast-forwarding, 2021-08-20). +cc Phillip (who wrote both commits).

-Peff