`wait_ready` not working correctly for Docker runtime

[jklaise]

Deploying a tempo model onto a Docker runtime and immediately calling it will result in an error:

Traceback (most recent call last):
  File "main.py", line 80, in <module>
    main()
  File "main.py", line 74, in main
    pred = object_detector.predict(img)
  File "/home/janis/.conda/envs/chrono/lib/python3.8/site-packages/tempo/serve/base.py", line 234, in predict
    return self.remote_with_spec(model_spec, *args, **kwargs)
  File "/home/janis/.conda/envs/chrono/lib/python3.8/site-packages/tempo/serve/base.py", line 269, in remote_with_spec
    response_raw = requests.post(endpoint, json=req, headers=headers, verify=ingress_options.verify_ssl)
  File "/home/janis/.conda/envs/chrono/lib/python3.8/site-packages/requests/api.py", line 119, in post
    return request('post', url, data=data, json=json, **kwargs)
  File "/home/janis/.conda/envs/chrono/lib/python3.8/site-packages/requests/api.py", line 61, in request
    return session.request(method=method, url=url, **kwargs)
  File "/home/janis/.conda/envs/chrono/lib/python3.8/site-packages/requests/sessions.py", line 530, in request
    resp = self.send(prep, **send_kwargs)
  File "/home/janis/.conda/envs/chrono/lib/python3.8/site-packages/requests/sessions.py", line 643, in send
    r = adapter.send(request, **kwargs)
  File "/home/janis/.conda/envs/chrono/lib/python3.8/site-packages/requests/adapters.py", line 498, in send
    raise ConnectionError(err, request=request)
requests.exceptions.ConnectionError: ('Connection aborted.', ConnectionResetError(104, 'Connection reset by peer'))
python main.py data/good_images/TfL_20200315_1300_00001.01251.jpg  5.10s user 1.51s system 32% cpu 20.344 total

This is despite the fact that model.wait_ready() is called as part of the call to deploy. The issue seems to be with the docker Python library.

@cliveseldon is there a specific bug or reference issue that describes the behaviour?