Remove a couple unused imports.

django/conf/__init__.py

@@ -7,7 +7,6 @@ a list of all possible variables.
 """
 
 import os
-import re
 import time     # Needed for Windows
 import warnings
 

django/contrib/sessions/tests.py

@@ -1,4 +1,4 @@
-from datetime import datetime, timedelta
+from datetime import timedelta
 import shutil
 import string
 import tempfile