commit 23d49d3e7e386bb2b26d5b944fc123f0f21ce0a6
author Benjamin Peterson <benjamin@python.org> Tue Aug 28 17:55:35 2012 -0400
committer Benjamin Peterson <benjamin@python.org> Tue Aug 28 17:55:35 2012 -0400
tree 2505d06c40de0283e39a5628108f72bf0549b7ff
parent 25cf30faf92b8b77c69a0fd4b839ceefbbaccc4f

use the stricter PyMapping_Check (closes #15801)

Objects/stringobject.c

diff --git a/Objects/stringobject.c b/Objects/stringobject.c
index fd2f630..7c4a86b 100644
--- a/Objects/stringobject.c
+++ b/Objects/stringobject.c
@@ -4254,7 +4254,7 @@
         arglen = -1;
         argidx = -2;
     }
-    if (Py_TYPE(args)->tp_as_mapping && !PyTuple_Check(args) &&
+    if (PyMapping_Check(args) && !PyTuple_Check(args) &&
         !PyObject_TypeCheck(args, &PyBaseString_Type))
         dict = args;
     while (--fmtcnt >= 0) {

Objects/unicodeobject.c

diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 59b138a..d40f2e4 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -8275,7 +8275,7 @@
         arglen = -1;
         argidx = -2;
     }
-    if (Py_TYPE(args)->tp_as_mapping && !PyTuple_Check(args) &&
+    if (PyMapping_Check(args) && !PyTuple_Check(args) &&
         !PyObject_TypeCheck(args, &PyBaseString_Type))
         dict = args;