def set_backtrace bt
      unless cause.nil?
        cause.backtrace.reverse.each do |line|
          if bt.last == line
            bt.pop
            next
          end
          break
        end
        bt.push "<<<CAUSED BY>>>: #{cause.class}: #{cause.message}"
        bt.concat cause.backtrace
      end
      super bt
    end
def set_backtrace bt
      unless cause.nil?
        cause.backtrace.reverse.each do |line|
          if bt.last == line
            bt.pop
            next
          end
          break
        end
        bt.push "<<<CAUSED BY>>>: #{cause.class}: #{cause.message}"
        bt.concat cause.backtrace
      end
      super bt
    end
Constructor.

 Modification of original method Error#set_backtrace
 to descend the full depth of the exception chain.