Monkey patch debug.rb to make source listing command work

debug_patch.rb

class DEBUGGER__
  def Context
    def display_list(b, e, file, line)
      stdout.printf "[%d, %d] in %s\n", b, e, file
      lines = SCRIPT_LINES__[file]
      if !lines
        lines = File.readlines file rescue nil
      end
      if lines and lines != true
        b.upto(e) do |n|
          if n > 0 && lines[n-1]
            if n == line
              stdout.printf "=> %d  %s\n", n, lines[n-1].chomp
            else
              stdout.printf "   %d  %s\n", n, lines[n-1].chomp
            end
          end
        end
      else
        stdout.printf "No sourcefile available for %s\n", file
      end
    end
  end
end