bug#12456: 24.2.50; Completion in `Info-goto-node' (cross-manual jump)

[Juri Linkov]

>> One question: if I do (from emacs -Q) `C-h r g ( e l i TAB TAB', I see
>> two completion candidates: "elisp" and "elisp.info".  This is a bug,
>> no?
>
> I doubt its usefulness too because it doesn't allow TAB to add the
> closing paren automatically as it does for a single completion,
> but as a comment in `Info-read-node-name-2' says:
>
>         ;; If the file name ends in a standard suffix,
>         ;; add the unsuffixed name as a completion option.
>
> So code adds both "elisp.info" with a standard suffix ".info"
> and the unsuffixed name "elisp".
>
> This means this intentionally is a feature, and not a bug.

But this doesn't mean it is a good feature.  Another similar command
`info-display-manual' doesn't add duplicates "elisp" and "elisp.info",
so when you do `M-x info-display-manual RET TAB' it displays a single
completion for every Info manual name without adding the suffix ".info".