sorry it took me a little while to get back to you.
I was able to identify a bug that exists server-side, you would end up seeing this with the Java client as well as the python client. We're planning on pushing a fix out this coming week. Your client should start to behave correctly as soon as that happens.
BTW, I'm not sure if you knew this already or not but there's a whole standalone python client that you can use to access the API from python as well. I thought that might be a bit more convenient for you than the client that's distributed as part of bq.py. You'll find a link to it on this page: https://developers.google.com/bigquery/client-libraries