Override mongoid-tree callback condition for default position

lib/tasks/new_ui.rake

@@ -92,6 +92,7 @@ namespace :new_ui do
   end
 
   task :reset_user_position => :environment do
+    User.where(email: /guest/).each{|d|d.update_attribute(:position, nil)}
     User.not_guest_user.each_with_index do |user, i|
       user.update_attribute(:position, i)
     end