[Catalog-sig] [Distutils] Metadata-Version in PKG-INFO

["Martin v. Löwis"]

> 2018 - LGPL 3.0 is released
> 2019 - Package X is licensed by LPGL (no version)
> 2020 - LPGL 4.0 is released
> 2021 - What's the license of the package X? LGPL 4.0

IANAL, but I don't believe this example; in addition, I
consider it fairly artificial. The LGPL recommends that
you include a verbatim copy of it in your source
distribution; if you do so, it seems fairly clear that
the license that you specified is the very version that
you include with your code, even if you don't mention
a version number explicitly.

OTOH, if you then also include the following text in
the source files (which the LGPL suggests that you do),
then clearly, you explicitly make it the user's choice
to pick a version:

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.

However, that wording is specific to the LGPL (and the GPL),
and does not apply to any other license.

Regards,
Martin