SF patch 1631942 by Collin Winter:
(a) "except E, V" -> "except E as V"
(b) V is now limited to a simple name (local variable)
(c) V is now deleted at the end of the except block
diff --git a/Tools/scripts/dutree.py b/Tools/scripts/dutree.py
index d938ae1..c9f6ea8 100755
--- a/Tools/scripts/dutree.py
+++ b/Tools/scripts/dutree.py
@@ -18,7 +18,7 @@
         total, d = store(size, comps, total, d)
     try:
         display(total, d)
-    except IOError, e:
+    except IOError as e:
         if e.errno != errno.EPIPE:
             raise