Comment by timonoko

This seems to be the bare mininum to run that python-mode automagically.

  (setq auto-mode-alist ; trigger python mode automatically
      (cons '("\\.py$" . python-mode) auto-mode-alist))
  (setq interpreter-mode-alist
      (cons '("python" . python-mode)
            interpreter-mode-alist))
  (autoload 'python-mode "python-mode" "Python editing mode." t)