github friendly commit messages in magit

gistfile1.el

;; github-friendly commit messages as per:
;; https://github.com/blog/926-shiny-new-commit-styles
(add-hook 'magit-log-edit-mode-hook 
          (lambda () 
            ;; highlight too-long commit summary
            (set (make-local-variable 'whitespace-line-column) 50)
            (set (make-local-variable 'whitespace-style) '(face lines-tail))
            (whitespace-mode 1)
            ;; autofill longer explanatory text
            (setq fill-column 72)
            (auto-fill-mode 1)))