merge 3.5 (#27774)

Misc/NEWS

@@ -107,6 +107,8 @@ Library
 - In the curses module, raise an error if window.getstr() or window.instr() is
   passed a negative value.
 
+- Issue #27774: Fix possible Py_DECREF on unowned object in _sre.
+
 - Issue #27760: Fix possible integer overflow in binascii.b2a_qp.
 
 - Issue #27758: Fix possible integer overflow in the _csv module for large record

Modules/_sre.c

@@ -2194,10 +2194,8 @@ _sre_SRE_Match_groupdict_impl(MatchObject *self, PyObject *default_value)
         if (!key)
             goto failed;
         value = match_getslice(self, key, default_value);
-        if (!value) {
-            Py_DECREF(key);
+        if (!value)
             goto failed;
-        }
         status = PyDict_SetItem(result, key, value);
         Py_DECREF(value);
         if (status < 0)