Remove debugging print (not triggered by test suite) and add XXX comment about...

Remove debugging print (not triggered by test suite) and add XXX comment about how the code should raise a SyntaxError.

Lib/compiler/transformer.py

@@ -811,8 +811,8 @@ class Transformer:
                 defaults.append(self.com_node(nodelist[i + 1]))
                 i = i + 2
             elif len(defaults):
+                # XXX This should be a syntax error.
                 # Treat "(a=1, b)" as "(a=1, b=None)"
-                print nodelist[i]
                 defaults.append(Const(None))
 
             i = i + 1