M-x mark-defun should mark top-level form

bug#13501: 24.3.50; mark-defun and friends don't work correctly in python
From: Ivan Andrus
Subject: bug#13501: 24.3.50; mark-defun and friends don't work correctly in python-mode
Date: Sat, 19 Jan 2013 22:21:38 +0100

Starting from emacs -Q create a buffer in python-mode with contents

with open('someFile') as f:
    data = f.read()

Place the cursor (say) after some and before File. Then run mark-defun
(e.g. with C-M-h). It will set mark at the end of the line and not move
point. Instead, it should select the entire block.