Fix seealso link to sets docs. Do not merge to Py3k.
diff --git a/Doc/library/stdtypes.rst b/Doc/library/stdtypes.rst
index f394b23..4fd7bbd 100644
--- a/Doc/library/stdtypes.rst
+++ b/Doc/library/stdtypes.rst
@@ -1608,7 +1608,7 @@
 
 .. seealso::
 
-   `Comparison to the built-in set types <comparison-to-builtin-set.html>`_
+   :ref:`comparison-to-builtin-set.html`
       Differences between the :mod:`sets` module and the built-in set types.