bug#24206: 25.1; Curly quotes generate invalid strings, leading to a segfault

[Eli Zaretskii]

> From: Phil <p.stephani2@gmail.com>
> Date: Thu, 11 Aug 2016 11:55:05 -0700
> 
> 
> Build is from the emacs-25 branch.
> 
> $ ./emacs -Q -eval "(progn (defface test nil \"\`\\240'\") (customize-face 
> 'test))"
> 
> character.h:703: Emacs fatal error: assertion failed: CHAR_VALID_P (ch)
> Fatal error 6: Aborted
> 
> I think this is serious enough to be release-blocking.  Seen in the wild
> with older versions of show-wspace.el.

Please show the real-life example where this rears its ugly head.  The
recipe (which is appreciated) is obscure enough to be easily avoided,
so it doesn't yet convince me this should block a release.  There's
always one more crash out there.

Thanks.