The Python world, including the `setuptools` package, has migrated to
the versioning scheme defined in PEP 440. Unfortunately, the versioning
of Jenkins plugins is less strict than that. As a consequence,
`pkg_resources.parse_version()` now rejects versions as invalid.
Fix `PluginVersion` by salvaging the implementation of the old
`LegacyVersion` class, which used to be part of the `packaging` library
prior to version 22.0. The code is licensed under a 2-clause BSD
licence.
For compatibility with older Python versions, remove type annotations
from the copied code.
Change-Id: Iaa057dcd81620fed861cb11bed534ff7f9ab3f32
Signed-off-by: Christoph Erhardt <ce+ubuntuone@sicherha.de>
876a2a928c