So I'm the author of both Byobu and purge-old-kernels. It's in Debian, because I help push it there after I push it to Ubuntu.
It's completely wrong that purge-old-kernels is in Byobu, rather than in the kernel or directly handled by dpkg/apt. Thanks for all the feedback here -- we'll get that cleaned up in 17.10!
It's completely wrong that purge-old-kernels is in Byobu, rather than in the kernel or directly handled by dpkg/apt. Thanks for all the feedback here -- we'll get that cleaned up in 17.10!