6.1.1  Automatically Deleting Unused Kernels

https://doc.opensuse.org/documentation/leap/reference/html/book.opensuse.reference/cha.tuning.multikernel.html#cha.tuning.multikernel.enable.keep

In the above referenced doc section, the following example of specifying a
particular kernel to be retained is provided:

" multiversion.kernels = latest,running,3.12.25.rc7-test

    Keep the latest kernel, the one currently running, and 3.12.25.rc7-test "

This is a poor illustrative choice, as a user trying to implement such a
feature on their own system may easily be mislead into mistakenly entering a
kernel name of, oh, say "4.8.14-1-default", which simply won't put a safeguard
on the desired kernel.   

User, who thought they'd been a smart monkey, becomes angry when they lose
their beloved kernel in a future updating session.  User then, instead of going
and pounding sand, turns to the openSUSE user forums to bitch and complain
about this grave injustice.[1]  

Fix it!  You've been warned.  :D

[1]
https://forums.opensuse.org/showthread.php/522368-multiversion-kernels-lost-the-kernel-I-specifically-instructed-zypper-to-keep