Incorrect unknown-license-reference detection and misleading license clarity score in recent scan of pyo3-0.20.1.tar.gz

[DennisClark]

A recent scan of pyo3-0.20.1.tar.gz from https://github.com/PyO3/pyo3/archive/refs/tags/v0.20.1.tar.gz produced generally good results but with a few misleading elements that result in a -20 score for Conflicting license categories.

One problem is the detection of unknown-license-reference which apparently is due to this sentence that appears in both the README and CHANGELOG files:

Dual-license PyO3 under either the Apache 2.0 OR the MIT license. This makes the project GPLv2 compatible. https://github.com/PyO3/pyo3/pull/3108

The following is more of a question than an issue: ScanCode also detected a generic-cla and that's fine but I want to make sure that a CLA Category does not result in a Conflicting license category state when the overall project license is Permissive. If the generic-cla is not causing the Conflicting license category state, then that is ok, but if it does that we have a problem, since there should not be any conflict in such a case.

Scan results attached.

pyo3-0.20.1.tar.gz_scan.zip

[DennisClark]

Rescanned using scancode-toolkit-v32.3.3.
Equivalent problems still persist. There is a detection of unknown-license-reference on line 255 of the README.md file, which is the sentence starting with "Unless" below:

## License

PyO3 is licensed under the [Apache-2.0 license](LICENSE-APACHE) or the [MIT license](LICENSE-MIT), at your option.

Python is licensed under the [Python License](https://docs.python.org/3/license.html).

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in PyO3 by you, as defined in the Apache License, shall be dual-licensed as above, without any additional terms or conditions.

The "Unless" sentence is simply stating that the choice of apache-2.0 OR mit also applies to new contributions, so it should not be treated as an unknown-license-reference.

Scan results attached.

pyo3-0.20.1-results.json.zip

[DennisClark]

Better scan results, this time including license-clarity-score, attached.

pyo3-0.20.1-results-c.json.zip