I also tested an upgrade from Ubuntu 19.04 to eoan and here we can see identifyObsoleteKernels actually attempting to do something wrong - suggesting to remove the kernel just installed. While this is because Ubuntu 19.04 and eoan currently have the same kernel version it still seems like an argument for dropping the function.

Relevant part of /var/log/dist-upgrade/main.log:

2019-06-19 14:51:33,447 DEBUG Obsolete: libisl19 libpoppler85 linux-headers-5.0.0-13 linux-headers-5.0.0-13-generic linux-image-5.0.0-13-generic linux-modules-5.0.0-13-generic linux-modules-extra-5.0.0-13-generic
2019-06-19 14:51:33,448 DEBUG Foreign:
2019-06-19 14:51:33,448 DEBUG identifyObsoleteKernels()
2019-06-19 14:51:36,381 DEBUG skipping running kernel linux-headers-5.0.0-13-generic
2019-06-19 14:51:36,381 DEBUG removing obsolete kernel 'linux-headers-5.0.0-17-generic'
2019-06-19 14:51:36,383 DEBUG skipping running kernel linux-image-5.0.0-13-generic
2019-06-19 14:51:36,383 DEBUG removing obsolete kernel 'linux-image-5.0.0-17-generic'
2019-06-19 14:51:36,387 DEBUG skipping running kernel linux-modules-5.0.0-13-generic
2019-06-19 14:51:36,387 DEBUG removing obsolete kernel 'linux-modules-5.0.0-17-generic'
2019-06-19 14:51:36,387 DEBUG skipping running kernel linux-modules-extra-5.0.0-13-generic
2019-06-19 14:51:36,388 DEBUG removing obsolete kernel 'linux-modules-extra-5.0.0-17-generic'
2019-06-19 14:51:37,872 DEBUG identifyObsoleteKernels found '{'linux-modules-extra-5.0.0-17-generic', 'linux-image-5.0.0-17-generic', 'linux-headers-5.0.0-17-generic', 'linux-modules-5.0.0-17-generic'}'
2019-06-19 14:51:37,872 DEBUG forced_obsoletes: ['desktop-effects', 'gnome-app-install', 'policykit-gnome', 'gnome-mount', 'linux-modules-extra-5.0.0-17-generic', 'linux-image-5.0.0-17-generic', 'linux-headers-5.0.0-17-generic', 'linux-modules-5.0.0-17-generic']
2019-06-19 14:51:38,179 DEBUG Unused dependencies: pppoeconf libisl19 pppconfig libpoppler85 ifupdown
2019-06-19 14:51:38,179 DEBUG remove_candidates: '{'linux-modules-extra-5.0.0-13-generic', 'pppoeconf', 'gnome-app-install', 'libisl19', 'desktop-effects', 'linux-image-5.0.0-13-generic', 'pppconfig', 'linux-headers-5.0.0-13-generic', 'linux-modules-5.0.0-17-generic', 'linux-headers-5.0.0-17-generic', 'policykit-gnome', 'ifupdown', 'linux-headers-5.0.0-13', 'gnome-mount', 'linux-image-5.0.0-17-generic', 'linux-modules-5.0.0-13-generic', 'libpoppler85', 'linux-modules-extra-5.0.0-17-generic'}'
2019-06-19 14:51:38,179 DEBUG Start checking for obsolete pkgs
2019-06-19 14:51:38,180 DEBUG skipping running kernel pkg 'linux-modules-extra-5.0.0-13-generic'
2019-06-19 14:51:38,180 DEBUG 'linux-modules-extra-5.0.0-13-generic' scheduled for remove but not safe to remove, skipping
2019-06-19 14:51:38,399 DEBUG skipping running kernel pkg 'linux-image-5.0.0-13-generic'
2019-06-19 14:51:38,399 DEBUG 'linux-image-5.0.0-13-generic' scheduled for remove but not safe to remove, skipping
2019-06-19 14:51:38,508 DEBUG skipping running kernel pkg 'linux-headers-5.0.0-13-generic'
2019-06-19 14:51:38,508 DEBUG 'linux-headers-5.0.0-13-generic' scheduled for remove but not safe to remove, skipping
2019-06-19 14:51:38,722 DEBUG package 'linux-modules-5.0.0-17-generic' produces an unwanted removal 'linux-image-generic', skipping
2019-06-19 14:51:38,978 DEBUG 'linux-modules-5.0.0-17-generic' scheduled for remove but not safe to remove, skipping
2019-06-19 14:51:39,186 DEBUG package 'linux-headers-5.0.0-17-generic' produces an unwanted removal 'linux-headers-generic', skipping
2019-06-19 14:51:39,440 DEBUG 'linux-headers-5.0.0-17-generic' scheduled for remove but not safe to remove, skipping
2019-06-19 14:51:39,993 DEBUG package 'linux-image-5.0.0-17-generic' produces an unwanted removal 'linux-image-generic', skipping
2019-06-19 14:51:40,505 DEBUG 'linux-image-5.0.0-17-generic' scheduled for remove but not safe to remove, skipping
2019-06-19 14:51:40,505 DEBUG skipping running kernel pkg 'linux-modules-5.0.0-13-generic'
2019-06-19 14:51:40,506 DEBUG 'linux-modules-5.0.0-13-generic' scheduled for remove but not safe to remove, skipping
2019-06-19 14:51:40,813 DEBUG package 'linux-modules-extra-5.0.0-17-generic' produces an unwanted removal 'linux-image-generic', skipping
2019-06-19 14:51:41,314 DEBUG 'linux-modules-extra-5.0.0-17-generic' scheduled for remove but not safe to remove, skipping
2019-06-19 14:51:41,314 DEBUG Finish checking for obsolete pkgs
2019-06-19 14:51:41,351 DEBUG The following packages are marked for removal: linux-headers-5.0.0-13 ifupdown linux-headers-5.0.0-13-generic pppoeconf libisl19 pppconfig libpoppler85