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

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

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.