org.el (org-refresh-stats-properties): Fix arithmetic error

* org.el (org-refresh-stats-properties): Fix arithmetic error.

Thanks to Gregor Zattler for reporting this.

lisp/org.el

@@ -9433,10 +9433,11 @@ call CMD."
 		 (concat org-outline-regexp-bol ".*"
 			 "\\(?:\\[\\([0-9]+\\)%\\|\\([0-9]+\\)/\\([0-9]+\\)\\]\\)")
 		 nil t)
-	   (setq stats (if (match-string 2)
-			   (/ (* (string-to-number (match-string 2)) 100)
-			      (string-to-number (match-string 3)))
-			 (string-to-number (match-string 1))))
+	   (setq stats (cond ((equal (match-string 3) "0") 0)
+			     ((match-string 2)
+			      (/ (* (string-to-number (match-string 2)) 100)
+				 (string-to-number (match-string 3))))
+			     (t (string-to-number (match-string 1)))))
 	   (org-back-to-heading t)
 	   (put-text-property (point) (progn (org-end-of-subtree t t) (point))
 			      'org-stats stats)))))))