HTTP_IF_MODIFIED_SINCE标头未传递给Rails应用程序（Nginx，Passenger）

I am trying to use the HTTP_IF_MODIFIED_SINCE header in my app to determine if resources are stale/fresh and render 200/304 in those cases. In my dev environment everything works fine but I can't for the life of me get it to work in production.I am trying to use the HTTP_IF_MODIFIED_SINCE h