Two more cases of switch(PySequence_Size()) without checking for case -1.

(Same problem as last checkin for SF bug 610610)
Need to clear the error and proceed.

Backport candidate

Python/exceptions.c

@@ -419,6 +419,9 @@ SystemExit__init__(PyObject *self, PyObject *args)
     case 1:
         code = PySequence_GetItem(args, 0);
         break;
+    case -1:
+        PyErr_Clear();
+        /* Fall through */
     default:
         Py_INCREF(args);
         code = args;
@@ -522,6 +525,10 @@ EnvironmentError__init__(PyObject *self, PyObject *args)
 	    goto finally;
 	}
 	break;
+
+    case -1:
+	PyErr_Clear();
+	break;
     }
 
     Py_INCREF(Py_None);