module Roda::RodaPlugins::Head::InstanceMethods

def call(*)

content length of 0.
Always use an empty response body for head requests, with a 
def call(*)
  res = super
  if @_request.head?
    body = res[2]
    if body.respond_to?(:close)
      res[2] = CloseLater.new(body)
    else
      res[2] = EMPTY_ARRAY
    end
  end
  res
end