Fix broken redirect (#467)

By default, flask turns redirects into absolute URLs. This is
undesired behaviour on Kubernetes, because the Pod's own IP address is
not really useful to any client that's not in the cluster (and even
within the cluster most clients will want to use the address of a
Service, not a Pod).

examples/python/guestbook/add.py

@@ -13,4 +13,6 @@ def main():
     # back to the list
     item = request.form['text']
     redisConnection.rpush('guestbook', item)
-    return redirect('/guestbook', code=303)
+    r = redirect('/guestbook', code=303)
+    r.autocorrect_location_header = False
+    return r