[O] Helm update brings "funcall: Symbol's value as variable is void: helm-walk-ignore-directories"

[Eduardo Mercovich]

Dear all.

After updating a 7 packages yesterday, including helm, I found my
org-mode (Emacs 24.3.1 in Linux) semi-functional with this message:

"funcall: Symbol's value as variable is void: helm-walk-ignore-directories"

This is defined in https://github.com/emacs-helm/helm/blob/master/helm-lib.el
I searched, but couldn't found something that helped me and my
knowledge is not enough to troubleshoot this issue (I'm a newbie on
the Emacs world and no programmer at all).

I would appreciate very much if someone can give me a few pointers to
start with.

Thanks a lot in advance... :)

-- 
e