bug#34969: 26.2; `emacs -Q` unable to copy \200's eight-bit detail buffer

[Van L]

> Eli Zaretskii writes:
> 
> [ ...] I still have hope someone will chime in and tell more
> about this, because even if some external software triggers this bug,
> we might still be able to do something in Emacs to prevent or
> alleviate that.

Japan is in a frenzy testing the next gengo Reiwa period this month.
The opportunity is there to include this test case, as part of that.