test_timeout_immediate2 fails

gistfile1.txt

$ ./ruby test/test_timeout.rb         
Run options: 

# Running tests:

[6/6] TestTimeout#test_timeout_immediate2 = 0.50 s                       
  1) Failure:
test_timeout_immediate2(TestTimeout) [test/test_timeout.rb:65]:
[RuntimeError] exception expected, not
Class: <#<Class:0x21da1fbc>>
Message: <"execution expired">
---Backtrace---
/home/shugo/local/lib/ruby/2.0.0/timeout.rb:53:in `async_interrupt_timing'
/home/shugo/local/lib/ruby/2.0.0/timeout.rb:53:in `timeout'
test/test_timeout.rb:58:in `block in test_timeout_immediate2'
---------------

Finished tests in 2.311519s, 2.5957 tests/s, 3.4609 assertions/s.
6 tests, 8 assertions, 1 failures, 0 errors, 0 skips

ruby -v: ruby 2.0.0dev (2012-12-06 trunk 38236) [i686-linux]