caucase.test: Make pylint happier.

caucase/test.py

@@ -331,7 +331,7 @@ class CaucaseTest(unittest.TestCase):
     Prepare test data directory and file paths, and start caucased as most
     tests will need to interact with it.
     """
-    global _clean_caucased_snapshot
+    global _clean_caucased_snapshot # pylint: disable=global-statement
     self._data_dir = data_dir = tempfile.mkdtemp(prefix='caucase_test_')
 
     self._client_dir = client_dir = os.path.join(data_dir, 'client')