Update test_util.py

Author: eric-wieser

test/test_util.py

@@ -22,7 +22,10 @@
     parse_date,
     tzoffset,
     from_timestamp)
-from test.lib import TestBase
+from test.lib import (
+    TestBase,
+    with_rw_repo,
+)
 from git.util import (
     LockFile,
     BlockingLockFile,