* lisp/progmodes/python.el: Preserve compatibility with Emacs-24

(python-mode): Don't assume eldoc-documentation-function has a non-nil
default.

lisp/ChangeLog

+2015-02-05  Stefan Monnier  <monnier@iro.umontreal.ca>
+
+	* progmodes/python.el: Try to preserve compatibility with Emacs-24.
+	(python-mode): Don't assume eldoc-documentation-function has a non-nil
+	default.
+
 2015-02-04  Sam Steingold  <sds@gnu.org>
 
 	* progmodes/python.el (python-indent-calculate-indentation): Avoid

lisp/progmodes/python.el

@@ -4684,8 +4684,12 @@ Arguments START and END narrow the buffer region to work on."
                                                  (current-column))))
          (^ '(- (1+ (current-indentation))))))
 
-  (add-function :before-until (local 'eldoc-documentation-function)
-                #'python-eldoc-function)
+  (if (null eldoc-documentation-function)
+      ;; Emacs<25
+      (setq (make-local-variable 'eldoc-documentation-function)
+            #'python-eldoc-function)
+    (add-function :before-until (local 'eldoc-documentation-function)
+                  #'python-eldoc-function))
 
   (add-to-list 'hs-special-modes-alist
                `(python-mode "^\\s-*\\(?:def\\|class\\)\\>" nil "#"