VTL: test/lisp.py Fix recursion error.

Accessing priority causes a recursion error.

Change-Id: Ic8cc5c9e198b7da955bc24ea116e9826004cad5e
Signed-off-by: Paul Vinciguerra <pvinci@vinciconsulting.com>
diff --git a/test/lisp.py b/test/lisp.py
index 7b803ad..2dace8f 100644
--- a/test/lisp.py
+++ b/test/lisp.py
@@ -64,7 +64,7 @@
 
     @property
     def priority(self):
-        return self.priority
+        return self._priority
 
     @property
     def weight(self):