bug#81625: 31.0.60; vc-git-status can return incorrect status information

Lester Longley via "Bug reports for GNU Emacs, the Swiss army knife of text editors" [15/Aug  1:33pm -04] wrote:
> X-Debbugs-Cc:
> --text follows this line--
>
> My ~/.emacs is tracked in a Git repo.
>
> The issue isn't specifically related to ~/.emacs; that's just how I
> encountered it.
>
> With:
>
>   [~] emacs -Q .emacs
>
> ... I noticed that the `vc-mode' portion of mode-line shows
> "Git!master", where "!" indicates "ignored".
>
> Importantly, my ~/.gitignore contains this pertinent line:
>
>   [~] grep emacs .gitignore
>   .emacs.d/
>
> This incorrect/misleading info. (i.e., `vc-mode' -> "Git!master",
> rather than "Git-master", when the file is current/clean w.r.t. its
> Git status)
> seems to result from the following command constructed by `vc-git-state':
>
>   [~] git status --porcelain -z --untracked-files --ignored -- .emacs
>   !! .emacs.d/elpa/vterm-20260626.1906/build/libvterm-prefix/src/libvterm/^@
>
> This latter path
> (.emacs.d/elpa/vterm-20260626.1906/build/libvterm-prefix/src/libvterm/)
> isn't special in any way that I'm aware of.
>
> In contrast, when ~/.emacs is modified, the "git status" command
> returns the following, and `vc-mode' indicates "Git:master", as
> expected.
>
>   [~] git status --porcelain -z --untracked-files --ignored -- .emacs
>    M .emacs^@!!
> .emacs.d/elpa/vterm-20260626.1906/build/libvterm-prefix/src/libvterm/^@
>
> Or, without "-z", for readability here:
>
>   [~] git status --porcelain --untracked-files --ignored -- .emacs
>    M .emacs
>   !! .emacs.d/elpa/vterm-20260626.1906/build/libvterm-prefix/src/libvterm/
>
> I'm using:
>
>   [~] git --version
>   git version 2.47.3

Please provide commands to create a populate a sample repository that
shows the problem, so that we can isolate it.

-- 
Sean Whitton