Pardon my interjection, my team works on these docs and so I might be able to comment up front. The Python 2.7 (only) and Go 1.9 (only) runtimes are "first generation" App Engine runtimes which use the App Engine Task Queues API which is internal to App Engine and not compatible with other products. The other runtimes, including the newer versions of Python and Go and also other supported languages such as Node, are "second generation" App Engine runtimes and instead of using App Engine-specific APIs, they have access to the Cloud-wide APIs such as Cloud Tasks and Cloud Pub/Sub which are what we recommend going forward.
In the specific case of pull queues, we instead recommend using the Cloud Pub/Sub API which provides much of the pull queue functionality separate from Task Queues. However, if this doesn't serve your needs, please reply to this email (or directly to me) with feedback as we're actively gathering customer feedback about any use cases that aren't covered by the new APIs.