Add a dead --irb option mentioning upgrade path

railties/lib/rails/commands/console.rb

@@ -17,6 +17,7 @@ def start
         opt.banner = "Usage: console [environment] [options]"
         opt.on('-s', '--sandbox', 'Rollback database modifications on exit.') { |v| options[:sandbox] = v }
         opt.on("--debugger", 'Enable ruby-debugging for the console.') { |v| options[:debugger] = v }
+        opt.on('--irb') { |v| abort '--irb option is no longer supported. Invoke `/your/choice/of/ruby script/console` instead' }
         opt.parse!(ARGV)
       end