Index: Python/bltinmodule.c
===================================================================
--- Python/bltinmodule.c	(revision 83896)
+++ Python/bltinmodule.c	(working copy)
@@ -974,11 +974,10 @@
         curseq = PyTuple_GetItem(args, i+1);
         sqp->it = PyObject_GetIter(curseq);
         if (sqp->it == NULL) {
-            static char errmsg[] =
-                "argument %d to map() must support iteration";
-            char errbuf[sizeof(errmsg) + 25];
-            PyOS_snprintf(errbuf, sizeof(errbuf), errmsg, i+2);
-            PyErr_SetString(PyExc_TypeError, errbuf);
+			if (PyErr_ExceptionMatches(PyExc_TypeError))
+				PyErr_Format(PyExc_TypeError,
+				  "argument %d to map() must support iteration",
+				  i+2);
             goto Fail_2;
         }
 
Index: Lib/test/test_functools.py
===================================================================
--- Lib/test/test_functools.py	(revision 83896)
+++ Lib/test/test_functools.py	(working copy)
@@ -297,6 +297,9 @@
         self.assertEqual(wrapper.attr, 'This is a different test')
         self.assertEqual(wrapper.dict_attr, f.dict_attr)
 
+class TestFailingIter:
+    def __iter__(self):
+        raise RuntimeError
 
 class TestReduce(unittest.TestCase):
 
@@ -337,6 +340,10 @@
         self.assertEqual(reduce(42, "1"), "1") # func is never called with one item
         self.assertEqual(reduce(42, "", "1"), "1") # func is never called with one item
         self.assertRaises(TypeError, reduce, 42, (42, 42))
+        class G:
+            pass
+        self.assertRaises(TypeError, reduce, lambda x, y: x+y, G())
+        self.assertRaises(RuntimeError, reduce, lambda x, y: x+y, TestFailingIter())
 
 class TestCmpToKey(unittest.TestCase):
     def test_cmp_to_key(self):
Index: Lib/test/test_builtin.py
===================================================================
--- Lib/test/test_builtin.py	(revision 83896)
+++ Lib/test/test_builtin.py	(working copy)
@@ -843,7 +843,13 @@
         def badfunc(x):
             raise RuntimeError
         self.assertRaises(RuntimeError, map, badfunc, range(5))
+        class G:
+            pass
+        self.assertRaises(TypeError, map, None, [], G())
+        self.assertRaises(RuntimeError, map, None, [], TestFailingIter())
+        
 
+
     def test_max(self):
         self.assertEqual(max('123123'), '3')
         self.assertEqual(max(1, 2, 3), 3)
@@ -1254,6 +1260,8 @@
         self.assertRaises(TypeError, reduce, add, []) # arg 2 must not be empty sequence with no initial value
         self.assertRaises(TypeError, reduce, add, "")
         self.assertRaises(TypeError, reduce, add, ())
+        self.assertRaises(TypeError, reduce, add, object()) 
+        self.assertRaises(RuntimeError, reduce, add, TestFailingIter())
         self.assertEqual(reduce(add, [], None), None)
         self.assertEqual(reduce(add, [], 42), 42)
 
@@ -1475,6 +1483,7 @@
         class G:
             pass
         self.assertRaises(TypeError, zip, a, G())
+        self.assertRaises(RuntimeError, zip, a, TestFailingIter())
 
         # Make sure zip doesn't try to allocate a billion elements for the
         # result list when one of its arguments doesn't say how long it is.
Index: Modules/_functoolsmodule.c
===================================================================
--- Modules/_functoolsmodule.c	(revision 83896)
+++ Modules/_functoolsmodule.c	(working copy)
@@ -23,8 +23,9 @@
 
     it = PyObject_GetIter(seq);
     if (it == NULL) {
-        PyErr_SetString(PyExc_TypeError,
-            "reduce() arg 2 must support iteration");
+		if (PyErr_ExceptionMatches(PyExc_TypeError))
+			PyErr_SetString(PyExc_TypeError,
+		    		"reduce() arg 2 must support iteration");
         Py_XDECREF(result);
         return NULL;
     }