Sinatra1.2.1とthin1.2.10を同時に使うと死ぬ

Sinatra Ruby

なんか問答無用でhttpアクセスした瞬間に落ちる

(eval):2:in `method_missing': undefined method `associate_callback_target' for #<Thin::Connection:0x102753d40> (NoMethodError)
	from /Users/sho/.rvm/gems/ruby-1.8.7-p334/gems/eventmachine-0.12.10/lib/em/connection.rb:39:in `new'
	from /Users/sho/.rvm/gems/ruby-1.8.7-p334/gems/eventmachine-0.12.10/lib/em/connection.rb:36:in `instance_eval'
	from /Users/sho/.rvm/gems/ruby-1.8.7-p334/gems/eventmachine-0.12.10/lib/em/connection.rb:36:in `new'
	from /Users/sho/.rvm/gems/ruby-1.8.7-p334/gems/eventmachine-0.12.10/lib/eventmachine.rb:1430:in `event_callback'
	from /Users/sho/.rvm/gems/ruby-1.8.7-p334/gems/eventmachine-0.12.10/lib/pr_eventmachine.rb:815:in `eventable_read'
	from /Users/sho/.rvm/gems/ruby-1.8.7-p334/gems/eventmachine-0.12.10/lib/pr_eventmachine.rb:812:in `times'
	from /Users/sho/.rvm/gems/ruby-1.8.7-p334/gems/eventmachine-0.12.10/lib/pr_eventmachine.rb:812:in `eventable_read'
	from /Users/sho/.rvm/gems/ruby-1.8.7-p334/gems/eventmachine-0.12.10/lib/pr_eventmachine.rb:369:in `crank_selectables'
	from /Users/sho/.rvm/gems/ruby-1.8.7-p334/gems/eventmachine-0.12.10/lib/pr_eventmachine.rb:369:in `each'
	from /Users/sho/.rvm/gems/ruby-1.8.7-p334/gems/eventmachine-0.12.10/lib/pr_eventmachine.rb:369:in `crank_selectables'
	from /Users/sho/.rvm/gems/ruby-1.8.7-p334/gems/eventmachine-0.12.10/lib/pr_eventmachine.rb:324:in `run'
	from /Users/sho/.rvm/gems/ruby-1.8.7-p334/gems/eventmachine-0.12.10/lib/pr_eventmachine.rb:318:in `loop'
	from /Users/sho/.rvm/gems/ruby-1.8.7-p334/gems/eventmachine-0.12.10/lib/pr_eventmachine.rb:318:in `run'
	from /Users/sho/.rvm/gems/ruby-1.8.7-p334/gems/eventmachine-0.12.10/lib/pr_eventmachine.rb:64:in `run_machine'
	from /Users/sho/.rvm/gems/ruby-1.8.7-p334/gems/eventmachine-0.12.10/lib/eventmachine.rb:256:in `run'
	from /Users/sho/.rvm/gems/ruby-1.8.7-p334/gems/thin-1.2.10/lib/thin/backends/base.rb:61:in `start'
	from /Users/sho/.rvm/gems/ruby-1.8.7-p334/gems/thin-1.2.10/lib/thin/server.rb:159:in `start'
	from /Users/sho/.rvm/gems/ruby-1.8.7-p334/gems/rack-1.2.2/lib/rack/handler/thin.rb:14:in `run'
	from /Users/sho/.rvm/gems/ruby-1.8.7-p334/gems/sinatra-1.2.1/lib/sinatra/base.rb:1208:in `run!'
	from /Users/sho/.rvm/gems/ruby-1.8.7-p334/gems/sinatra-sugar-0.5.0/lib/sinatra/sugar.rb:130:in `run!'
	from /Users/sho/.rvm/gems/ruby-1.8.7-p334/gems/sinatra-1.2.1/lib/sinatra/main.rb:25
	from development.ru:14


解決策

set :server, 'webrick'

悲しい