[AIRFLOW-6892] Fix broken non-wheel releases

[kaxil]

Our non-wheel releases on pypi are broken

pip install --no-binary apache-airflow apache-airflow

will install a version that does this:

FileNotFoundError: [Errno 2] No such file or directory: '/home/ash/.virtualenvs/clean/lib/python3.7/site-packages/airflow/serialization/schema.json'

There are no issues with wheel package. Pip install wheel package if available and unless you use "--no-binary"specifically

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Issue link: AIRFLOW-6892

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[potiuk]

Good that you caught it @kaxil!

[kaxil]

Credits to @ashb for actually finding this bug :)

Just surprising though that sdist and bdist_wheel use different things to decide what to include in the package

[potiuk]

Yeah. Well, they are different things in fact. But indeed I am also unimpressed by the level of consistency and documentation correctness of the setuptools. It's half-baked at most. Seems that part of python never got the love it deserved.