Loren Arthur

> Thanks for the contribution, and I apologize for being slow to review it. There's subtle code here and it needs a lot of attention. > > This looks like...

@bdarnell The initial motivation behind this PR was to get the `current_task` api to work with `gen.coroutines` in order to support context tracing with the newrelic-python-agent. https://github.com/newrelic/newrelic-python-agent/blob/51af0379f032737d307b03650e15945218fe94e7/newrelic/core/trace_cache.py#L127