That one was a mistake.

Objects/unicodeobject.c

@@ -6380,7 +6380,7 @@ static PyMethodDef unicode_methods[] = {
     /* Order is according to common usage: often used methods should
        appear first, since lookup is done sequentially. */
 
-    {"encode",  unicode_encode, METH_VARARGS, encode__doc__},
+    {"encode", (PyCFunction) unicode_encode, METH_VARARGS, encode__doc__},
     {"replace", (PyCFunction) unicode_replace, METH_VARARGS, replace__doc__},
     {"split", (PyCFunction) unicode_split, METH_VARARGS, split__doc__},
     {"rsplit", (PyCFunction) unicode_rsplit, METH_VARARGS, rsplit__doc__},