* lisp/progmodes/python.el (python-indent-guess-indent-offset):

Avoid corner-case error.

Fixes: debbugs:15975

lisp/ChangeLog

 2013-11-26  Glenn Morris  <rgm@gnu.org>
 
+	* progmodes/python.el (python-indent-guess-indent-offset):
+	Avoid corner-case error.  (Bug#15975)
+
 	Preload leim-list.el.  (Bug#4789)
 	* loadup.el: Load leim-list.el when found.
 	* startup.el (normal-top-level): Skip re-loading leim/leim-list.el.

lisp/progmodes/python.el

@@ -676,7 +676,7 @@ AFTER-LINE.")
                  (goto-char block-end)
                  (python-util-forward-comment)
                  (current-indentation))))
-          (if indentation
+          (if (and indentation (not (zerop indentation)))
               (set (make-local-variable 'python-indent-offset) indentation)
             (message "Can't guess python-indent-offset, using defaults: %s"
                      python-indent-offset)))))))