SF #1444030: Fix several potential defects found by Coverity.
(reviewed by Neal Norwitz)
diff --git a/Objects/stringobject.c b/Objects/stringobject.c
index 0030ac7..e2b7603 100644
--- a/Objects/stringobject.c
+++ b/Objects/stringobject.c
@@ -3276,7 +3276,7 @@
     return list;
 
  onError:
-    Py_DECREF(list);
+    Py_XDECREF(list);
     return NULL;
 }