class Gem::RemoteFetcher

def fetch_http uri, last_modified = nil, head = false, depth = 0
  fetch_type = head ? Net::HTTP::Head : Net::HTTP::Get
  response   = request uri, fetch_type, last_modified do |req|
    headers.each { |k,v| req.add_field(k,v) }
  end
  case response
  when Net::HTTPOK, Net::HTTPNotModified then
    response.uri = uri if response.respond_to? :uri
    head ? response : response.body
  when Net::HTTPMovedPermanently, Net::HTTPFound, Net::HTTPSeeOther,
       Net::HTTPTemporaryRedirect then
    raise FetchError.new('too many redirects', uri) if depth > 10
    location = URI.parse response['Location']
    if https?(uri) && !https?(location)
      raise FetchError.new("redirecting to non-https resource: #{location}", uri)
    end
    fetch_http(location, last_modified, head, depth + 1)
  else
    raise FetchError.new("bad response #{response.message} #{response.code}", uri)
  end
end