PBR should not rely on pkg_resources anymore

[Gaetan Semet]

Hello.
pkg_resources library is no more recommended to be used, or at least we could expect an end of life pretty soon.

Its replacement is importlib-resource which is an optional component to install with pip for Python <3.7 and became part of the default distribution for 3.7+.

A Migration guide is provided to get rid of support of pkg_resources [1].

PBR should begging supporting using importlib-resource, at first as a backup in case pkg_resource is not packaged correctly (ex: I have this error in a pynsist package):

  ...
    from jira import JIRA
  File "...pkgs\jira\__init__.py", line 6, in <module>
    _v = VersionInfo('jira').semantic_version()
  File "...pkgs\pbr\version.py", line 462, in semantic_version
    self._semantic = self._get_version_from_pkg_resources()
  File "...\pkgs\pbr\version.py", line 439, in _get_version_from_pkg_resources
    import pkg_resources
  ModuleNotFoundError: No module named 'pkg_resources'

Here my proposal:
- keep pkg_resource the default
- if the previous exception occurs, try with importlib.resource

[1] https://importlib-resources.readthedocs.io/en/latest/migration.html#migration

[Marcel Telka (marcel-telka)]

Is there any plan to drop dependency on pkg_resources soon?

Thank you.