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

Hi Sean,

On Tue, Aug 18, 2026 at 7:13 AM Sean Whitton <[email protected]> wrote:
> Lester Longley via "Bug reports for GNU Emacs, the Swiss army knife of text editors" [15/Aug  1:33pm -04] wrote:
> > ...
> > 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.

Here's a reproduction recipe (now verified on Emacs 32.0.50 built this morning):

  [~] cd /tmp; git init 81625; cd 81625
  ...

  [/tmp/81625] touch blat; git add blat; git commit -m New blat
  ...

  [/tmp/81625] mkdir blatter; cd blatter; git init dummy; cd -
  ...

  [/tmp/81625] echo "blatter/" > .gitignore

  [/tmp/81625] git status --porcelain --untracked-files --ignored -- blat
  !! blatter/dummy/

  # now observe the bug: opening file "blat" wrongly shows vc-mode
"Git!master", versus expected "Git-master"
  [/tmp/81625] emacs -Q /tmp/81625/blat

I.e., it's the presence of a Git repo within an Git-ignored directory,
which matches the applicable Git pathspec, which leads to such "!!
..." records from git status.

More such repos. result in more corresponding "!! ..." records:

  [/tmp/81625] mkdir blatter; cd blatter; git init dumdum; cd -
  ...

  [/tmp/81625] git status --porcelain --untracked-files --ignored -- blat
  !! blatter/dumdum/
  !! blatter/dummy/

In my original report, this situation was caused by libvterm, which
happened to download a repo. in the process of building that module.

Regards,
Lester