def set_ancestor_tasks(task, ancestor = nil)
      task.options[:ancestors] += (ancestor || task).options[:is]
      (ancestor || task).options[:is].each do |parent_task|
        set_ancestor_tasks(task, @tasks[parent_task])
      end
    end
def set_ancestor_tasks(task, ancestor = nil)
      task.options[:ancestors] += (ancestor || task).options[:is]
      (ancestor || task).options[:is].each do |parent_task|
        set_ancestor_tasks(task, @tasks[parent_task])
      end
    end
Set the ancestors on task.

 @param [Task] task The task for which the ancestors are set
 @param [Task] ancestor The ancestor to process. This is the recursive parameter