Hello,
With David's help, I've built a better pattern to consume python-cicoclient alongside JJB. A major goal of this work was to avoid using curl calls to Github.
In summary, it uses a builder to get nodes and a publisher to release nodes without leaking. I've created a Github repo[1] with a real-world job (actually a copy of one of our jobs).
Please let me know if you find this useful and if you have suggestions for improvements. As I convert more jobs to JJB, it will be more flexible for requesting more than one node and more than one OS version.
[1]: https://github.com/nigelbabu/centos-ci-sample
-- nigelb