=== trac/wiki/model.py
==================================================================
--- trac/wiki/model.py  (revision 4818)
+++ trac/wiki/model.py  (local)
@@ -44,7 +44,8 @@
         cursor = db.cursor()
         if version:
             cursor.execute("SELECT version,text,readonly FROM wiki "
-                           "WHERE name=%s AND version=%s",
+                           "WHERE name=%s AND version<=%s "
+                           "ORDER BY version DESC LIMIT 1",
                            (name, int(version)))
         else:
             cursor.execute("SELECT version,text,readonly FROM wiki "
=== trac/wiki/web_ui.py
==================================================================
--- trac/wiki/web_ui.py  (revision 4818)
+++ trac/wiki/web_ui.py  (local)
@@ -350,6 +350,9 @@
 
         version = req.args.get('version')
         if version:
+            if int(version) != page.version:
+                req.redirect(self.env.href.wiki(page.name,
+                                                version=page.version))
             # Ask web spiders to not index old versions
             req.hdf['html.norobots'] = 1