Comment 3 for bug 1605160

Definitely no manual interaction, fresh install recently.

# apt-mark showauto ^linux-image-.*
linux-image-4.4.0-21-generic
linux-image-4.4.0-22-generic
linux-image-4.4.0-24-generic
linux-image-4.4.0-28-generic
linux-image-4.4.0-31-generic
linux-image-extra-4.4.0-28-generic
linux-image-extra-4.4.0-31-generic
linux-image-generic

# apt-mark showmanual ^linux-image-.*

(no output..)

# cat /etc/apt/apt.conf.d/01autoremove-kernels
// DO NOT EDIT! File autogenerated by /etc/kernel/postinst.d/apt-auto-removal
APT::NeverAutoRemove
{
   "^linux-image-4\.4\.0-28-generic$";
   "^linux-image-4\.4\.0-31-generic$";
   "^linux-headers-4\.4\.0-28-generic$";
   "^linux-headers-4\.4\.0-31-generic$";
   "^linux-image-extra-4\.4\.0-28-generic$";
   "^linux-image-extra-4\.4\.0-31-generic$";
   "^linux-signed-image-4\.4\.0-28-generic$";
   "^linux-signed-image-4\.4\.0-31-generic$";
   "^kfreebsd-image-4\.4\.0-28-generic$";
   "^kfreebsd-image-4\.4\.0-31-generic$";
   "^kfreebsd-headers-4\.4\.0-28-generic$";
   "^kfreebsd-headers-4\.4\.0-31-generic$";
   "^gnumach-image-4\.4\.0-28-generic$";
   "^gnumach-image-4\.4\.0-31-generic$";
   "^.*-modules-4\.4\.0-28-generic$";
   "^.*-modules-4\.4\.0-31-generic$";
   "^.*-kernel-4\.4\.0-28-generic$";
   "^.*-kernel-4\.4\.0-31-generic$";
   "^linux-backports-modules-.*-4\.4\.0-28-generic$";
   "^linux-backports-modules-.*-4\.4\.0-31-generic$";
   "^linux-tools-4\.4\.0-28-generic$";
   "^linux-tools-4\.4\.0-31-generic$";
};
/* Debug information:
# dpkg list:
ii linux-image-4.4.0-21-generic 4.4.0-21.37 amd64 Linux kernel image for version 4.4.0 on 64 bit x86 SMP
ii linux-image-4.4.0-22-generic 4.4.0-22.40 amd64 Linux kernel image for version 4.4.0 on 64 bit x86 SMP
ii linux-image-4.4.0-24-generic 4.4.0-24.43 amd64 Linux kernel image for version 4.4.0 on 64 bit x86 SMP
ii linux-image-4.4.0-28-generic 4.4.0-28.47 amd64 Linux kernel image for version 4.4.0 on 64 bit x86 SMP
ii linux-image-4.4.0-31-generic 4.4.0-31.50 amd64 Linux kernel image for version 4.4.0 on 64 bit x86 SMP
rc linux-image-extra-4.4.0-21-generic 4.4.0-21.37 amd64 Linux kernel extra modules for version 4.4.0 on 64 bit x86 SMP
rc linux-image-extra-4.4.0-22-generic 4.4.0-22.40 amd64 Linux kernel extra modules for version 4.4.0 on 64 bit x86 SMP
rc linux-image-extra-4.4.0-24-generic 4.4.0-24.43 amd64 Linux kernel extra modules for version 4.4.0 on 64 bit x86 SMP
ii linux-image-extra-4.4.0-28-generic 4.4.0-28.47 amd64 Linux kernel extra modules for version 4.4.0 on 64 bit x86 SMP
ii linux-image-extra-4.4.0-31-generic 4.4.0-31.50 amd64 Linux kernel extra modules for version 4.4.0 on 64 bit x86 SMP
ii linux-image-generic 4.4.0.31.33 amd64 Generic Linux kernel image
# list of installed kernel packages:
4.4.0-21-generic 4.4.0-21.37
4.4.0-22-generic 4.4.0-22.40
4.4.0-24-generic 4.4.0-24.43
4.4.0-28-generic 4.4.0-28.47
4.4.0-31-generic 4.4.0-31.50
# list of different kernel versions:
4.4.0-31.50
4.4.0-28.47
4.4.0-24.43
4.4.0-22.40
4.4.0-21.37
# Installing kernel: ()
# Running kernel: 4.4.0-31.50 (4.4.0-31-generic)
# Last kernel: 4.4.0-31.50
# Previous kernel: 4.4.0-28.47
# Kernel versions list to keep:
4.4.0-28.47
4.4.0-31.50
# Kernel packages (version part) to protect:
4\.4\.0-28-generic
4\.4\.0-31-generic
*/