bug#30277: 26.0.91; Infinite recursion in python-nav-beginning-of-statement

[Dmitry Gutov <dgutov@yandex.ru>]

Hi!

On 1/29/18 1:42 AM, Ola Nilsson wrote:
> The infinite recursion is triggered when the first line of a
> python-mode buffer starts with space and ends with a backslash.
> 
> With emacs -Q
> 
> * create a new buffer
> * M-x python-mode
> * Insert SPACE \ ENTER
> 
> => Lisp nesting exceeds ‘max-lisp-eval-depth’
> 
> The infinite recursion is also triggered if the first line of a narrowed
> region starts with space and ends on a backslash.

This seems to fix it for me. Please test thoroughly, I rarely ever use 
python-mode myself.

diff --git a/lisp/progmodes/python.el b/lisp/progmodes/python.el
index 5baf6e0f80..ff8269d970 100644
--- a/lisp/progmodes/python.el
+++ b/lisp/progmodes/python.el
@@ -1474,7 +1474,7 @@ python-nav-forward-defun
  (defun python-nav-beginning-of-statement ()
    "Move to start of current statement."
    (interactive "^")
-  (back-to-indentation)
+  (forward-line 0)
    (let* ((ppss (syntax-ppss))
           (context-point
            (or
@@ -1489,6 +1489,7 @@ python-nav-beginning-of-statement
               (python-info-line-ends-backslash-p))
             (forward-line -1)
             (python-nav-beginning-of-statement))))
+  (back-to-indentation)
    (point-marker))

  (defun python-nav-end-of-statement (&optional noend)