New issue by ahesford on void-packages repository

https://github.com/void-linux/void-packages/issues/21323

Description:
The move to drop the default `python_version=2` in favor of no default, in combination with the move to derive the `pycompile_version` value from `python_version`, has broken builds that declare `pycompile_dirs` without `python_version`.

The hook `common/hooks/post-install/04-create-xbps-metadata-scripts.sh` tries to discover the `pycompile_version` from the existence of `usr/lib/pythonX.Y`. However, this directory will not exist if a package installs Python code somewhere else. In these cases, when `pycompile_dirs` is nonempty by `python_version` is not set, the hook will fail.

The fix involves:
1. Finding the list of packages that declare `pycompile_dirs`;
2. Eliminating from the list those packages that also declare `python_version`;
3. Further eliminating those packages that install files into `usr/lib/pythonX.Y` for any version `X.Y`; and
4. Manually adding `python_version=2` to the remaining templates. This will restore prior build behavior for those packages.

I will dig into this as soon as I have time. In the meantime, please merge as many reasonable PRs that add explicit `python_version` to individual templates as possible to avoid duplicate PRs and potential merge conflicts.