class Sinatra::Response

def finish
  if status.to_i / 100 == 1
    headers.delete "Content-Length"
    headers.delete "Content-Type"
  elsif Array === body and not [204, 304].include?(status.to_i)
    headers["Content-Length"] = body.inject(0) { |l, p| l + Rack::Utils.bytesize(p) }.to_s
  end
  # Rack::Response#finish sometimes returns self as response body. We don't want that.
  status, headers, result = super
  result = body if result == self
  [status, headers, result]
end