X py: Don't import MySQLdb where it is not needed

neo/tests/__init__.py

@@ -26,7 +26,7 @@ import sys
 import tempfile
 import unittest
 import weakref
-import MySQLdb
+#import MySQLdb
 import transaction
 
 from contextlib import contextmanager

neo/tests/functional/__init__.py

@@ -22,7 +22,6 @@ import ZODB
 import socket
 import signal
 import random
-import MySQLdb
 import sqlite3
 import unittest
 import tempfile