When removing a linux-image-extra package, kernel post-installation scripts including /etc/kernel/postinst.d/update-notifier will be run. That is a symbolic link to /usr/share/update-notifier/notify-reboot-required, which can be modified to fix this bug.
When removing a linux-image-extra package, kernel post-installation scripts including /etc/kernel/ postinst. d/update- notifier will be run. That is a symbolic link to /usr/share/ update- notifier/ notify- reboot- required, which can be modified to fix this bug.