bug#31448: M-x list-input-methods ; broken link from within chinese-py-b5 to chinese-py

[Eli Zaretskii]

> From: Van L <van@scratch.space>
> Date: Mon, 14 May 2018 10:41:25 +1000
> 
> The following sequence of interactions causes the error:
> 
>   describe-character-set: Invalid charset: "chinese-py”
> 
> The steps to reproduce this bug is as follows:
> 
>   M-x list-input-methods
>   ↳ chinese-py-b5 ; click this link
>     ↳ chinese-py  ; click this link causes the error
>       ↳ describe-character-set: Invalid charset: "chinese-py"

A much easier way to reproduce the same problem:

  emacs -Q
  C-h C-\ chinese-py-b5 RET
  Click the link "chinese-py" in the *Help* buffer

Looks like some code makes a button there intended to describe a
charset, but the text talks about an input method, not a charset.

I'm looking into this.