plugin XEP-0050: form returned by completed command are now managed

src/plugins/plugin_xep_0050.py

@@ -255,11 +255,16 @@ class XEP_0050(object):
         if status in [XEP_0050.STATUS.COMPLETED, XEP_0050.STATUS.CANCELED]:
             # the command session is finished, we purge our session
             del self.requesting[session_id]
-            return None
+            if status == XEP_0050.STATUS.COMPLETED:
+                session_id = None
+            else:
+                return None
         remote_session_id = command_elt.getAttribute('sessionid')
         if remote_session_id:
             session_data['remote_id'] = remote_session_id
         data_elt = command_elt.elements(data_form.NS_X_DATA, 'x').next()
+        if session_id is None:
+            return xml_tools.dataFormResult2XMLUI(data_elt)
         form = data_form.Form.fromElement(data_elt)
         return  xml_tools.dataForm2XMLUI(form, self.__requesting_id, session_id=session_id)