bug#65049: Minor update to the repro steps

[Dmitry Gutov]

On 28/08/2023 15:12, Eli Zaretskii wrote:
> > Try edebug-instrumenting vc-diff-internal and then calling vc-root-diff
> > anywhere (C-x v D). When the execution reaches the line that we have
> > been discussing, you'll see that (vc-coding-system-for-diff (car files))
> > evaluates to 'undecided because (car files) is a directory.
> >
> > So this mechanism is always unused in vc-root-diff.
> OK, but in that case 'undecided' is the best guess we can come up
> with.  It basically lets Emacs guess when it actually sees the stuff
> in the diffs, while reading it into a buffer.

Yes, and if it's good enough for the (possibly?) most-frequently used 
out of the vc-*-diff commands, then perhaps we don't need the additional 
detection logic?

Since its introduction 30 years ago indeed the situation has changed a 
lot, with UTF-8 and its ubiquity. Removing the extra complication would 
make code a little easier to read, and reduce variability when 
reproducing problems. But there's no hurry, of course.