Comment 20 for bug 1898729

bionic is good, as soon as I add the bionic-proposed sources.list entry (containing 1.37~18.04.10), the package is treated as essential.

# apt autoremove
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be REMOVED:
  efibootmgr grub-common grub-efi-amd64 grub-efi-amd64-bin grub-efi-amd64-signed grub2-common libefiboot1 libefivar1 libfreetype6 mokutil os-prober sbsigntool secureboot-db shim shim-signed
0 upgraded, 0 newly installed, 15 to remove and 0 not upgraded.
After this operation, 33.2 MB disk space will be freed.
Do you want to continue? [Y/n] ^C
# sudo vim /etc/apt/sources.list
# apt update
[...]
# apt autoremove
[...]
0 upgraded, 0 newly installed, 0 to remove and 29 not upgraded.
# apt remove shim-signed
[...]
WARNING: The following essential packages will be removed.
This should NOT be done unless you know exactly what you are doing!
  shim-signed
0 upgraded, 0 newly installed, 1 to remove and 28 not upgraded.
After this operation, 1397 kB disk space will be freed.
You are about to do something potentially harmful.
To continue type in the phrase 'Yes, do as I say!'