What's the point of order-only dependencies in `rake`?

[x-yuri]

The ones added by #269. If you're adding that, then you probably want file tasks to ignore order-only dependencies?

rake/lib/rake/file_task.rb

Lines 32 to 41 in 5c60da8

 def out_of_date?(stamp) 
   all_prerequisite_tasks.any? { |prereq| 
     prereq_task = application[prereq, @scope] 
     if prereq_task.instance_of?(Rake::FileTask) 
       prereq_task.timestamp > stamp || @application.options.build_all 
     else 
       prereq_task.timestamp > stamp 
     end 
   } 
 end