Fixed reference leak when read truncated pickle.
diff --git a/Modules/_pickle.c b/Modules/_pickle.c
index 6ff16bb..c357dcc 100644
--- a/Modules/_pickle.c
+++ b/Modules/_pickle.c
@@ -5115,8 +5115,10 @@
         return -1;
 
     if ((len = _Unpickler_Readline(self, &s)) >= 0) {
-        if (len < 2)
+        if (len < 2) {
+            Py_DECREF(module_name);
             return bad_readline();
+        }
         class_name = PyUnicode_DecodeASCII(s, len - 1, "strict");
         if (class_name != NULL) {
             cls = find_class(self, module_name, class_name);