def alternates=(alts)
      alts.each do |alt|
        unless File.exist?(alt)
          raise "Could not set alternates. Alternate path #{alt} must exist"
        end
      end

      if alts.empty?
        self.git.fs_write('objects/info/alternates', '')
      else
        self.git.fs_write('objects/info/alternates', alts.join("\n"))
      end
    end
def alternates=(alts)
      alts.each do |alt|
        unless File.exist?(alt)
          raise "Could not set alternates. Alternate path #{alt} must exist"
        end
      end

      if alts.empty?
        self.git.fs_write('objects/info/alternates', '')
      else
        self.git.fs_write('objects/info/alternates', alts.join("\n"))
      end
    end
Sets the alternates
   +alts+ is the Array of String paths representing the alternates

 Returns nothing