zendframework/zf2 — pull request #3070 by necromant2005 (2012-11-26 13:43:31+00:00)
Title: Fix default value unavailable exception for in-build php classes

Main trouble: https://bugs.php.net/bug.php?id=50798
Getting Reflection for default value for internal php extension
I caught this in GearmanClient
The best solution is using "isDefaultValueAvailable" method
http://www.php.net/manual/en/reflectionparameter.isdefaultvalueavailable.php