Remove legacy py2.6 backwards logging compat. code

We no longer provide support for py2.6 so we don't
need the logging compatibility code to exist anymore.

Change-Id: Iaefab67fd8b4e222475d99f57c2c3a7a5ce07d6e

taskflow/logging.py

@@ -17,7 +17,6 @@
 from __future__ import absolute_import
 
 import logging
-import sys
 
 _BASE = __name__.split(".", 1)[0]
 
@@ -49,45 +48,8 @@ class _BlatherLoggerAdapter(logging.LoggerAdapter):
         self.warning(msg, *args, **kwargs)
 
 
-# TODO(harlowja): we should remove when we no longer have to support 2.6...
-if sys.version_info[0:2] == (2, 6):
-
-    class _FixedBlatherLoggerAdapter(_BlatherLoggerAdapter):
-        """Ensures isEnabledFor() exists on adapters that are created."""
-
-        def isEnabledFor(self, level):
-            return self.logger.isEnabledFor(level)
-
-    _BlatherLoggerAdapter = _FixedBlatherLoggerAdapter
-
-    # Taken from python2.7 (same in python3.4)...
-    class _NullHandler(logging.Handler):
-        """This handler does nothing.
-
-        It's intended to be used to avoid the
-        "No handlers could be found for logger XXX" one-off warning. This is
-        important for library code, which may contain code to log events. If a
-        user of the library does not configure logging, the one-off warning
-        might be produced; to avoid this, the library developer simply needs
-        to instantiate a _NullHandler and add it to the top-level logger of the
-        library module or package.
-        """
-
-        def handle(self, record):
-            """Stub."""
-
-        def emit(self, record):
-            """Stub."""
-
-        def createLock(self):
-            self.lock = None
-
-else:
-    _NullHandler = logging.NullHandler
-
-
 def getLogger(name=_BASE, extra=None):
     logger = logging.getLogger(name)
     if not logger.handlers:
-        logger.addHandler(_NullHandler())
+        logger.addHandler(logging.NullHandler())
     return _BlatherLoggerAdapter(logger, extra=extra)