rails encoding problem

require 'net/http'

url = "http://data.linz.gv.at/katalog/population/abstammung/2012/auslg_2012.csv"
File.open('output', "w:UTF-8") do |f|
content = Net::HTTP.get_response(URI.parse(url)).body
f.write(content.force_encoding("UTF-8"))
end