Hi!

While rebuilding the python related packages against the Python 3.15rc1
version we found that joblib fails to build from source [1].

In order to fix the issue, I had to:
- Run the tests in autopkg tests with the conftest file (Fixes #1140861)
- Backport loky's _decode_message function to support Python 3.14+
   (Fixes #1141207).
- Change the condition for using multiprocessing in the random parallel
   example (needs to be forwarded upstream).

I applied these fixes in the sandbox [2] to be able to build the
packages that depend on joblib, please consider applying the patch to
support the upcoming 3.15 version.

Happy hacking,

[1]: https://debusine.debian.net/debian/r-python-python3.15/artifact/4496152/
[2]: https://debusine.debian.net/debian/r-python-python3.15/