bug#19665:

[Carlos Pita]

It seems to me that the problem is in python-nav--beginning-of-defun.
Specifically there is (< arg 0) guard that is testing the wrong case
(end-of-line should be called for the backwards case, not the forward
one):

        (found
           (progn
-            (when (and (< arg 0)
+            (when (and (> arg 0)
                        (python-info-looking-at-beginning-of-defun))
               (end-of-line 1))
             (while (and (funcall re-search-fn