From emacs -Q, running the following code:

    (add-to-list 'custom-theme-load-path default-directory)
    (load-theme 'extend-inherit t)
    (ediff-files "/usr/share/common-licenses/LGPL-2" "/usr/share/common-licenses/LGPL-2.1")

… gives the following results with commit 1c29ba0340: