next-single-property-change and narrowed buffers

[Magnus Henoch]

Please describe exactly what actions triggered the bug
and the precise symptoms of the bug:

The docsting of next-single-property-change promises that it will
never return a value equal to the position given, but it does if the
buffer is narrowed and the next property change occurs after the
narrowed region.  Test case:

(defun test-nspc ()
  (interactive)
  (with-current-buffer (get-buffer-create "*test-nspc*")
    (fundamental-mode)
    (erase-buffer)
    (insert (make-string 100 ?\ ))
    (add-text-properties 25 50 '(test-nspc t))
    (narrow-to-region 1 49)
    (let ((pos (point-min)))
      (while pos
        (message "pos is %s" pos)
        (let ((old-pos pos))
          (setq pos (next-single-property-change pos 'test-nspc))
          (when (and pos (<= pos old-pos))
            (error "%s is <= %s" pos old-pos)))))))

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If you would like to further debug the crash, please read the file
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In GNU Emacs 22.0.50.4 (powerpc-unknown-netbsd3.99.23, X toolkit, Xaw3d scroll 
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 of 2006-08-21 on zemdatav
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