cleanup: remove pre-python 2.6 code

nose2/util.py

@@ -11,23 +11,8 @@
 import sys
 import traceback
 import platform
-
-try:
-    from inspect import isgeneratorfunction  # new in 2.6
-except ImportError:
-    import inspect
-    try:
-        from compiler.consts import CO_GENERATOR
-    except ImportError:
-        # IronPython doesn't have a complier module
-        CO_GENERATOR = 0x20
-    # backported from Python 2.6
-
-    def isgeneratorfunction(func):
-        return bool((inspect.isfunction(func) or inspect.ismethod(func)) and
-                    func.func_code.co_flags & CO_GENERATOR)
-
 import six
+from inspect import isgeneratorfunction  # new in 2.6
 
 
 __unittest = True