Oh really...
All test passed in my environment.
Please let me check.
Thank you!

---
For your information:
My environment is like following.
$cat /cpu/version
Linux version 3.2.0-40-virtual (buildd@allspice) (gcc version 4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu5) ) #64-Ubuntu SMP Mon Mar 25 21:42:18 UTC 2013
$fluentd --version => fluentd 0.10.41
$ruby -v              => ruby 1.9.3p484 (2013-11-22 revision 43786) [x86_64-linux]
$gem -v              => 1.8.23