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/Lib/warnings.py b/Lib/warnings.py
index b7fac69..c0a96d6 100644
--- a/Lib/warnings.py
+++ b/Lib/warnings.py
@@ -192,7 +192,7 @@
     for arg in args:
         try:
             _setoption(arg)
-        except _OptionError, msg:
+        except _OptionError as msg:
             print >>sys.stderr, "Invalid -W option ignored:", msg
 
 # Helper for _processoptions()