added missing import

--HG--
branch : trunk
diff --git a/jinja2/utils.py b/jinja2/utils.py
index d9a45a8..87b3d13 100644
--- a/jinja2/utils.py
+++ b/jinja2/utils.py
@@ -9,6 +9,7 @@
     :license: BSD, see LICENSE for more details.
 """
 import re
+import sys
 import string
 try:
     from thread import allocate_lock