# File lib/faraday/connection.rb, line 224
    def build_url(url, extra_params = nil)
      uri          = URI.parse(url.to_s)
      if @path_prefix && uri.path !~ /^\//
        new_path = @path_prefix.size > 1 ? @path_prefix.dup : ''
        new_path << "/#{uri.path}" unless uri.path.empty?
        uri.path = new_path
      end
      uri.host   ||= @host
      uri.port   ||= @port
      uri.scheme ||= @scheme

      params = @params.dup.merge_query(uri.query)
      params.update extra_params if extra_params
      uri.query = params.empty? ? nil : params.to_query

      uri
    end