def get_proxy_from_env
    env_proxy = ENV['http_proxy'] || ENV['HTTP_PROXY']

    return nil if env_proxy.nil? or env_proxy.empty?

    uri = URI.parse(normalize_uri(env_proxy))

    if uri and uri.user.nil? and uri.password.nil? then
      # Probably we have http_proxy_* variables?
      uri.user = escape(ENV['http_proxy_user'] || ENV['HTTP_PROXY_USER'])
      uri.password = escape(ENV['http_proxy_pass'] || ENV['HTTP_PROXY_PASS'])
    end

    uri
  end
#
Returns an HTTP proxy URI if one is set in the environment variables.