AFAICT the culprit is linux-image-extra-<version>-generic;
at least on Trusty postrm and postinst are identical; both iterate blindly through /etc/kernel/postinst.d thereby calling 'update-notifier', which is a symlink to /usr/share/update-notifier/notify-reboot-required
FWIW this happens on Trusty as well.
AFAICT the culprit is linux-image- extra-< version> -generic; postinst. d thereby calling 'update-notifier', which is a symlink to /usr/share/ update- notifier/ notify- reboot- required
at least on Trusty postrm and postinst are identical; both iterate blindly through /etc/kernel/