bug#46368: Completion vs. "*" buffer names

[Gregory Heytings]

> Look at the bottom line of the image.
> Here we see completion will never work,
> because the "*" is missing from the start of the string.
>
> (Our cursor is at the end of the line there at the bottom.)
> How did we end up this way?
> Well we just hit "un<TAB>".
> emacs-version "27.1"

Does (setq read-buffer-completion-ignore-case t) solve your problem?

If not, could you provide a recipe, starting with emacs -Q, to reproduce 
the problem?