Fixed missing NullHanlder in Python 2.6

Author: expobrain

git/util.py

@@ -19,6 +19,14 @@
 except ImportError:
     from unittest2 import SkipTest
 
+if not hasattr(logging, 'NullHandler'):
+    class NullHandler(logging.Handler):
+        def emit(self, record):
+            pass
+
+    logging.NullHandler = NullHandler
+
+
 from gitdb.util import (# NOQA @IgnorePep8
     make_sha,
     LockedFD,               # @UnusedImport