engine/lib/locomotive/mongoid/patches.rb

require 'mongoid'

## various patches
module Mongoid #:nodoc:

  module Document

    def update_child_with_noname(child, clear = false)
      name = child.association_name
      return if name.blank? # fix a weird bug with mongoid-acts-as-tree
      update_child_without_noname(child, clear)
    end

    alias_method_chain :update_child, :noname

  end
end