Re: rev-parse --show-toplevel broken during exec'ed rebase?

[Vitali Lovich <vlovich@gmail.com>]

On Thu, Jul 12, 2018 at 8:23 AM Junio C Hamano <gitster@pobox.com> wrote:
>
> Vitali Lovich <vlovich@gmail.com> writes:
>
> > Repro (starting with cwd within git project):
> >> (cd xdiff; git rev-parse --show-toplevel)
> > ... path to git repository
> >> git rebase -i 18404434bf406f6a6f892ed73320c5cf9cc187dd
> > # Stop at some commit for editing
> >> (cd xdiff; git rev-parse --show-toplevel)
> > ... path to git repository
> >> git rebase 18404434bf406f6a6f892ed73320c5cf9cc187dd -x "(cd xdiff; git rev-parse --show-toplevel)"
> > ... path to git repository/xdiff !!!
> >
> > This seems like incorrect behaviour to me since it's a weird
> > inconsistency (even with other rebase contexts) & the documentation
> > says "Show the absolute path of the top-level directory." with no
> > caveats.
>
> Does it reproduce with older rebase (say from v2.10 days), too?
>
> I suspect that the above is because "git rebase" is exporting
> GIT_DIR without exporting GIT_WORK_TREE.  When the former is given
> without the latter, that tells Git that you are at the top-level of
> the working tree (if that is not the case, you also export the
> latter to tell Git where the top-level is).
>
> I suspect that "git rebase" before the ongoing piecemeal rewrite to
> C started (or scripted Porcelain in general) refrained from
> exporting GIT_DIR to the environment, and if my suspicion is correct,
> older "git rebase" would behave differently to your test case.

Unfortunately I don't have an older git version handy to test this out.