Fix a regression that broke debugging Stackless tasklets
Fix a regression that broke debugging Stackless tasklets

Commit b92dca6 introduced a new local variable "debugger", but didn't
initialise it.

fabioz/PyDev.Debugger,fabioz/PyDev.Debugger,fabioz/PyDev.Debugger,fabioz/PyDev.Debugger,fabioz/PyDev.Debugger