Re: [PATCH] sequencer.c: set GIT_WORK_TREE in run_git_checkout

> When rebasing in a subdirectory of a worktree, Git fails due to a dirty
> worktree:
>
>   error: The following untracked working tree files would be overwritten
> by merge:
>           a/b/c
>   Please move or remove them before you merge.
>
> This occurs because "git rebase" invokes a "git checkout" without
> propagating the GIT_WORK_TREE environment variable, causing the worktree
> to be assumed to be ".". This was not an issue until bc3ae46b42 (rebase:
> do not attempt to remove startup_info->original_cwd, 2021-12-09), when
> the .dir of the "git checkout" child process was changed such that it no
> longer runs at the root of the worktree.
>
> Propagate GIT_WORK_TREE to the "git checkout" child process and test
> that rebase in a subdirectory of a worktree succeeds.
>
> Signed-off-by: Glen Choo <chooglen@google.com>
> ---
> Here is a fix for the bug I found in [1]. I didn't look through the rest
> of the "preserve cwd" thread for other possible bugs pertaining to
> worktrees, but I didn't find any during a cursory glance at sequencer.c.
>
> I'm also not sure if this is the idiomatic way to do it since, I assume,
> we'd always want to propagate GIT_WORK_TREE, but this is identical to
> how do_exec() sets GIT_WORK_TREE in the same file (perhaps this is
> something that should be refactored).
>
> [1] https://lore.kernel.org/git/kl6lilu71rzl.fsf@chooglen-macbookpro.roam.corp.google.com