Shebang and python packages

[Phil]

Hi all,

It seems to be convention not to include python itself as a
propagated-input in python packages?

However the default-python version is included as a native-input for the
python-build-system - this means any shebangs are hardcoded to whatever
the current version of python may be.

Given this hardcoding, why isn't it also convention to package the version
of python that has been used to patch the shebangs as part of the
package?

I tend to build manifests containing my python app, and python
itself to run the app.  Originally I thought this was necessary to decouple the
app from a specific version of python, but assuming I'm right about
the patching of shebangs, this seems to be misguided - as any entry points
within the app will have been hardcoded to use a version of python at
build time, irrespective of the python version in the manifest?

Can anyone clarify best practice and reasoning behind it?

Thanks,
Phil.