* lisp/simple.el (kill-new): Fix logic of kill-do-not-save-duplicates.
Instead of setting `replace' to t and replacing the same string
with itself, don't do certain actions when
kill-do-not-save-duplicates is non-nil and string is equal to car
of kill-ring: don't call menu-bar-update-yank-menu, don't push
interprogram-paste strings to kill-ring, and don't push the input
argument `string' to kill-ring.
http://lists.gnu.org/archive/html/emacs-devel/2010-06/msg00072.html