diff -r 782599274bf9 tools/python/xen/util/xsm/flask/flask.py
--- a/tools/python/xen/util/xsm/flask/flask.py	Tue Sep 30 10:14:54 2008 +0100
+++ b/tools/python/xen/util/xsm/flask/flask.py	Tue Oct 07 15:37:16 2008 -0400
@@ -35,7 +35,10 @@
     return ssidref
 
 def set_security_label(policy, label):
-    return label
+    if label:
+        return label
+    else:
+        return ""
 
 def ssidref2security_label(ssidref):
     label = ssidref2label(ssidref)