Code completion for ipython causes exception (sometimes)

The first time a user tries to use code completion for the iPython interpreter the notebook will hang for a long time (I believe it's waiting for the websocket to return) and will get the pop up below (tested on the latest docker image for apache zeppelin found on docker hub)

After this code completion usually works but will sometimes throw this error again. This error will happen again if the user restarts the interpreter.

We do not get this error when attempting code completion for the python interpreter. I've traced through the code as well as I can and believe the issue is that code completion is trying to use the PythonInterpreter class to get the completion list, but since we're using the iPython interpreter the PythonInterpreter class is not instantiated, and therefore get the NPE. I could be wrong though.