yas-activate-extra-mode does not update keybindings

[lua-vr]

It seems (after some tests and comparing the yas-activate-extra-mode and yas-minor-mode code) that yas-activate-extra-mode does not activate the extra mode snippet's keybindings when they exist.

The missing bit from yas-minor-mode that make bindings work is:

         ;; Set the `yas--direct-%s' vars for direct keymap expansion
         ;;
         (dolist (mode (yas--modes-to-activate))
           (let ((name (intern (format "yas--direct-%s" mode))))
             (set-default name nil)
             (set (make-local-variable name) t)))

and indeed, if I append

(let ((name (intern (format "yas--direct-%s" mode))))
  (set-default name nil)
  (set (make-local-variable name) t))

to the yas-activate-extra-mode function, keybindings are loaded as expected.