Curl::Multi.download error handling issue

[sriedel]

If an error was encountered, Curl::Multi.download does an

      ensure                                                                    
         # ...                                                                  
        raise errors unless errors.empty?                                       
      end  

However errors is an array and ruby cannot raise an array of errors:

2.2.3 :001 > raise StandardError.new
StandardError: StandardError
        from (irb):1
        from /home/sr/.rvm/rubies/ruby-2.2.3/bin/irb:11:in `<main>'
2.2.3 :002 > raise [ StandardError.new, StandardError.new ]
TypeError: exception class/object expected
        from (irb):2:in `raise'
        from (irb):2
        from /home/sr/.rvm/rubies/ruby-2.2.3/bin/irb:11:in `<main>'