bug#69056: 30.0.50; history-add-new-input and recursive minibuffers

[Stefan Monnier]

> 1. emacs -Q
> 2. (setq enable-recursive-minibuffers t)
> 3. M-y
> 4. In the minibuffer (with the prompt "Yank from kill-ring: "),
>    type M-x calendar RET (or any other command).
> 5. M-x M-p
>    Expected: "calendar" is inserted in the minibuffer.
>    Observed: error saying "Beginning of history; no preceding item".
>
> The problem is that the minibuffer history of M-x isn't recorded when
> you invoke M-x from within the minibuffer of read-from-kill-ring (M-y).
> The reason is that read-from-kill-ring let binds history-add-new-input,
> and that affects all recursive minibuffers as well, so no minibuffer
> history is recorded until you exit the first (non-recursive) minibuffer.

I suspect this can bite in more cases, including cases which don't
involve setting `enable-recursive-minibuffers` to t.
We should probably change the way `history-add-new-input` works so it's
attached to a particular minibuffer rather than being dynbound.


        Stefan