Multiple modules required by apache-airflow is missing when installed with `python setup.py install`

[tuoping]

After installation with python setup.py install, performed in the git cloned latest master branch, the command airflow -h raises the following error

    import httpx
  File "/opt/anaconda3/lib/python3.8/site-packages/httpx-0.19.0-py3.8.egg/httpx/__init__.py", line 2, in <module>
    from ._api import delete, get, head, options, patch, post, put, request, stream
  File "/opt/anaconda3/lib/python3.8/site-packages/httpx-0.19.0-py3.8.egg/httpx/_api.py", line 4, in <module>
    from ._client import Client
  File "/opt/anaconda3/lib/python3.8/site-packages/httpx-0.19.0-py3.8.egg/httpx/_client.py", line 9, in <module>
    from ._auth import Auth, BasicAuth, FunctionAuth
  File "/opt/anaconda3/lib/python3.8/site-packages/httpx-0.19.0-py3.8.egg/httpx/_auth.py", line 10, in <module>
    from ._models import Request, Response
  File "/opt/anaconda3/lib/python3.8/site-packages/httpx-0.19.0-py3.8.egg/httpx/_models.py", line 11, in <module>
    import charset_normalizer
ModuleNotFoundError: No module named 'charset_normalizer'

And pip installation of the "NotFound" modules leads to various "version incompatible" issues.