Bug#979631: APT::Get::AutomaticRemove::Kernels: also allow keeping N newest

[積丹尼 Dan Jacobson <jidanni@jidanni.org>]

Package: apt
Version: 2.1.16

Regarding (/usr/share/doc/apt/examples/configure-index)

     AutomaticRemove "<BOOL>" {
        "Kernels" "<BOOL>";     // Allow removing kernels even if not removing other packages (true for dist-upgrade)
     };

I would also have another variable, with a digit argument,
e.g., "2" would keep the two latest unused kernels around.

In fact the default should be at least "1".

The new "0" policy, will certainly result in users needing to take their
computers to the repair shop, as all it will take is one bad kernel,
and the next time the user tries to boot... they will no longer be able to!

Yes, for the last few years it has not happened. But many of us remember
when it has. And we are thankful to the elders who always told us to
keep a few spare kernels around, that we can choose from LILO or GRUB,
in case the default fails.

(Sure: "Just boot from a thumb drive then." Well often those kernels
lying around one's house are already incompatible with the filesystem,
etc. and it takes an Internet connection to get new ones, but we can't
boot so no Internet, and we live on a mountain...)