bug in info related to invisible text.

[Luc Teirlinck]

Do: 

emacs-21.3.50 -q --eval "(blink-cursor-mode 0)"
C-h i m emacs RETURN s bug RETURN.

Keep doing "s RETURN".  (Or C-x z z z z ...)

All goes well until suddenly, the cursor gets "stuck", although there
are plenty of further occurrences of "bug" nearby.

Now do M-x vis-mode. Now we see what is going on.  Moreover,
now repeated applications of "s RETURN" carry us to plenty of
further occurrences of "bug".

Sincerely,

Luc.