Re: scratch/backend-completion 1af23aade6f: More tweaks to external-completion.el after Stefan's comments

[Stefan Monnier]

> +Despite the original authors's best efforts,
> +TRY-COMPLETION-FUNCTION is still a poorly understood
> +implementation detail.  If you understand what it's for, you

FWIW, I'm not really the original author of try-completion.
More specifically, the `try-completion` function itself predates my
involvement with Emacs, and its generalization in
`partial-completion-mode` as well.  I do take responsability for
`completion-try-completion`, admittedly, where I tried to give an
"official" interface to that operation, but I was just trying to
preserve existing semantics.


        Stefan