+Keymaps are no longer fset, which means they need to be referred to in
+define-key directly (without quotes). If your Emacs configuration has a
+keybinding like:
+ (define-key 'notmuch-show-mode-map "7" 'foo)
+you should change it to:
+ (define-key notmuch-show-mode-map "7" 'foo)
+