Error when building the testing docker images

We the users try to build the test docker images using the Python file in /comnetsemu/test_containers$ python3 build.py

The building process fails, and the following Error appears:

*** Build minimal test images.
- Build image with tag: dev_test:latest, Dockerfile path: ./Dockerfile.dev_test
Traceback (most recent call last):
  File "build.py", line 64, in <module>
    main()
  File "build.py", line 51, in main
    ret = build_image(client, tag, dockerfile, retry)
  File "build.py", line 30, in build_image
    client.images.build(
  File "/usr/lib/python3/dist-packages/docker/models/images.py", line 279, in build
    resp = self.client.api.build(**kwargs)
  File "/usr/lib/python3/dist-packages/docker/api/build.py", line 263, in build
    response = self._post(
  File "/usr/lib/python3/dist-packages/docker/utils/decorators.py", line 46, in inner
    return f(self, *args, **kwargs)
  File "/usr/lib/python3/dist-packages/docker/api/client.py", line 226, in _post
    return self.post(url, **self._set_request_timeout(kwargs))
  File "/usr/local/lib/python3.8/dist-packages/requests/sessions.py", line 637, in post
    return self.request("POST", url, data=data, json=json, **kwargs)
  File "/usr/local/lib/python3.8/dist-packages/requests/sessions.py", line 589, in request
    resp = self.send(prep, **send_kwargs)
  File "/usr/local/lib/python3.8/dist-packages/requests/sessions.py", line 703, in send
    r = adapter.send(request, **kwargs)
  File "/usr/local/lib/python3.8/dist-packages/requests/adapters.py", line 633, in send
    conn = self.get_connection_with_tls_context(
  File "/usr/local/lib/python3.8/dist-packages/requests/adapters.py", line 489, in get_connection_with_tls_context
    conn = self.poolmanager.connection_from_host(
  File "/usr/lib/python3/dist-packages/urllib3/poolmanager.py", line 234, in connection_from_host
    return self.connection_from_context(request_context)
  File "/usr/lib/python3/dist-packages/urllib3/poolmanager.py", line 244, in connection_from_context
    pool_key_constructor = self.key_fn_by_scheme[scheme]
KeyError: 'http+docker'