bug#54359: 29.0.50; [PATCH] Undo breaking change to project interface

[Juri Linkov]

>> There is no bug.
>
> I noticed all emacs developers, myself included, say this about their
> own code.
>
> It's fine.  Of the four people in the world using project.el, I suspect
> only half of them rely on `(cdr (project-current))` being an atom
> instead of a list.

I'm the fifth user of project.el and after that change
just quietly replaced in my code

-                 (let ((project (cdr (project-current nil directory))))
-                   (when project

with more correct code that doesn't rely on internal data structure

+                 (let* ((project (project-current nil directory))
+                        (root (when project (project-root project))))