bug#63648: 29.0.90; project.el: with switch-use-entire-map, switch-project errors on non-project commands

[Juri Linkov <juri@linkov.net>]

> 1. (setq project-switch-use-entire-map t)
> 2. C-x p p some/project RET
> 3. At the prompt, C-x C-j
> 4. Errors with:
> project-switch-project: Wrong type argument: commandp, 1
>
> Desired behavior: commands should run with default-directory of the
> project-root.  So C-x C-j should open dired in the project root.
>
> I specifically ran into this when doing
> C-x p p some/project RET C-x v +
>
> because I wanted to immediately pull that project.  Intuitively it made
> sense to me that that should work, it would be nice if it did actually
> work.

This should be possible to implement by using 'set-transient-map'.

> (Tangential further thought: I wonder if we could make C-x p work as a
> prefix for all commands automatically, so for example C-x p C-x C-j
> would open the project root, C-x p M-& would run a shell command in the
> root, etc.  That would be neat.)

IOW, like 'C-x p p' but without asking for another project.  Doable as well.