SF bug 433228: repr(list) woes when len(list) big.
Gave Python linear-time repr() implementations for dicts, lists, strings.
This means, e.g., that repr(range(50000)) is no longer 50x slower than
pprint.pprint() in 2.2 <wink>.

I don't consider this a bugfix candidate, as it's a performance boost.

Added _PyString_Join() to the internal string API.  If we want that in the
public API, fine, but then it requires runtime error checks instead of
asserts.
diff --git a/Objects/stringobject.c b/Objects/stringobject.c
index bcf5147..24443d8 100644
--- a/Objects/stringobject.c
+++ b/Objects/stringobject.c
@@ -1031,6 +1031,23 @@
 	return res;
 }
 
+PyObject *_PyString_Join(PyObject *sep, PyObject *x)
+{
+	PyObject* args;
+	PyObject* result = NULL;
+
+	assert(sep != NULL && PyString_Check(sep));
+	assert(x != NULL);
+	args = PyTuple_New(1);
+	if (args != NULL) {
+		Py_INCREF(x);
+		PyTuple_SET_ITEM(args, 0, x);
+		result = string_join((PyStringObject *)sep, args);
+		Py_DECREF(args);
+	}
+	return result;
+}
+
 static long
 string_find_internal(PyStringObject *self, PyObject *args, int dir)
 {