Ignore handling logic for importlib_metadata (mypy, tests/plugins)

[khalidmammadov]

Part of #19891

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[potiuk]

I think we have PY38 constant for that in `airflow': @khalidmammadov .

Also @ashb - I recall discussions we had about it, I think it makes sense to based it on Python version

[ashb]

Yeah, someone (i forget who, maybe Martjin Peiters? sp?) recommended the approach TP says -- always try the third part first, as that API is stable and predictable.)

[uranusjr]

The problem is that importlib.metadata is unstable (the official term is provisional) before 3.10, and not everything in importlib_metadata is available in importlib.metadata. So if we want to switch to, say, the 3.9 version of importlib.metadata, we’d bump the python_version marker in setup.cfg, but after this change we’d also need to change a ton of if-imports due to that change. Try-imports are easier because it’d always try the third-party version first, regardless of the Python version.

If we want to change try-imports to if-imports, it’s probably better to always use importlib_metadata for all versions prior to 3.10, when the stdlib importlib.metadata enters stable state.

Also I believe PY38 would not work because Mypy uses AST detection to perform type-time conditional magic, and would not understand what PY38 means correctly.

[potiuk]

The problem is that importlib.metadata is unstable (the official term is provisional) before 3.10

That would explain some of the behaviours seen before :)

[khalidmammadov]

The problem is that importlib.metadata is unstable (the official term is provisional) before 3.10, and not everything in importlib_metadata is available in importlib.metadata. So if we want to switch to, say, the 3.9 version of importlib.metadata, we’d bump the python_version marker in setup.cfg, but after this change we’d also need to change a ton of if-imports due to that change. Try-imports are easier because it’d always try the third-party version first, regardless of the Python version.

If we want to change try-imports to if-imports, it’s probably better to always use importlib_metadata for all versions prior to 3.10, when the stdlib importlib.metadata enters stable state.

Also I believe PY38 would not work because Mypy uses AST detection to perform type-time conditional magic, and would not understand what PY38 means correctly.

I will revert and try to fix MyPy issues different way

[ashb]

@khalidmammadov Please read https://cbea.ms/git-commit/ (linked to from our contributing guide) and try to give more useful commit messages in future.

[khalidmammadov]

@khalidmammadov Please read https://cbea.ms/git-commit/ (linked to from our contributing guide) and try to give more useful commit messages in future.

Do you mean commit message or PR description/title?