This really should been part of my previous commit
(Sun Nov 8 14:16:43 2015 -0500, git commit
3812e17978).
\f
* Changes in Specialized Modes and Packages in Emacs 25.1
+** New function `bookmark-set-no-overwrite' bound to C-x r M.
+It raises an error if a bookmark of that name already exists,
+unlike `bookmark-set' which silently updates an existing bookmark.
+
** JSON
---
*** `json-pretty-print' and `json-pretty-print-buffer' now maintain