Use a set to track negotiated features.

Added guards to prevent renegotiating STARTTLS or SASL in cases where
servers don't behave properly.

sleekxmpp/features/feature_bind/bind.py

@@ -53,6 +53,8 @@ class feature_bind(base_plugin):
         self.xmpp.set_jid(response['bind']['jid'])
         self.xmpp.bound = True
 
+        self.features.add('bind')
+
         log.info("Node set to: %s" % self.xmpp.boundjid.full)
 
         if 'session' not in features['features']: