bug#65089: 30.0.50; shell-command filename completion unexpected behavior change

[Eli Zaretskii <eliz@gnu.org>]

> Date: Sat, 5 Aug 2023 07:46:16 -0300
> From: Mauro Aranda <maurooaranda@gmail.com>
> 
> Before running emacs, setup a directory tree like this:
> mkdir bug bug/foo-1 bug/foo-2 bug/foo-1/bar bug/foo-2/bar
> under HOME, for simplicity.
> 
> Now, with emacs -Q:
> M-!
> ls ~/bug/bar
> Put point between "/" and "b" of "bar" and type TAB
> emacs says "No match", but I expected it to offer completions, foo-1 and
> foo-2.
> 
> That was the behavior, at least in Emacs 28.  Reverting the following
> commit, returns this behavior for me:
> 
> commit a9941269683fe50673d0aa81feefb7a9d3d8a6b9
> Author: Augusto Stoffel <arstoffel@gmail.com>
> Date:   Thu Sep 8 11:09:42 2022 +0200
> 
>      pcomplete: Generate completions from --help messages
> 
>      * lisp/pcomplete.el (pcomplete-from-help): New function (and hash
>      table) to get pcomplete candidates from help messages.
>      (pcomplete-here-using-help): Helper function to define pcomplete for
>      simple commands
>      (pcomplete-completions-at-point): Provide annotation-function and
>      company-docsig properties.
>      * lisp/pcmpl-git.el: New file, provides pcomplete for Git.
>      * lisp/pcmpl-gnu.el: Add pcomplete for awk, gpg and gdb, emacs and
>      emacsclient.
>      * lisp/pcmpl-linux.el: Add pcomplete for systemctl and journalctl.
>      * lisp/pcmpl-rpm.el: Add pcomplete for dnf.
>      * lisp/pcmpl-unix.el: Add pcomplete for sudo and most commands found
>      in GNU Coreutils.
>      * lisp/pcmpl-x.el: Add pcomplete for tex, pdftex, latex, pdflatex,
>      rigrep and rclone.
>      * test/lisp/pcomplete-tests.el (pcomplete-test-parse-gpg-help,
>      pcomplete-test-parse-git-help): Tests for the new functions.
> 
> 
> And my current workaround is to move pcomplete-completions-at-point to
> the end in shell-dynamic-complete-functions, following what was done in
> Bug#34330.

Adding Augusto and Stefan to the discussion.