Tootfinder

One of the goals I've set for further development of #Python eclasses in #Gentoo was to avoid needless complexity. Unfortunately, the subject matter sometimes requires them. However, many of the functions added lately were already manually done in ebuilds for years.
We've started disabling plugin autoloading years ago. First we just did that for individual packages that caused issues. Then, for these where tests ended up being really slow. Finally, pretty much anywhere `python_test()` was declared. Doing it all manually was particularly cumbersome — all I needed for `EPYTEST_PLUGINS` is a good idea how to generalize it.
Similarly, `EPYTEST_XDIST` was added after we have been adding manually `epytest -p xdist -n "$(makeopts_jobs)" --dist=worksteal` — and while at it, I've added `EPYTEST_JOBS` to override the job count.
Perhaps `EPYTEST_TIMEOUT` wasn't that common. However, it was meant to help CI systems that could otherwise get stuck on hanging test.
Similarly, "standard library" version (like `3.9`) matching to `python_gen_cond_dep` was added after a long period of explicitly stating `python3_9 pypy3`. As an extra benefit, this also resolved the problem that at the time `pypy3` could mean different Python versions.