"Le paquet 'docker-ce' n'a pas de candidat à l'installation" en 18.04

Je suis le guide officiel d'installation de Docker pour docker-ce sur Ubuntu.

Quand j'arrive à sudo apt install docker-ce Je reçois E: Package 'docker-ce' has no installation candidate :

$ sudo apt-get update
Hit:1 http://gb.archive.ubuntu.com/ubuntu bionic InRelease
Hit:2 http://gb.archive.ubuntu.com/ubuntu bionic-updates InRelease
Hit:3 http://gb.archive.ubuntu.com/ubuntu bionic-backports InRelease
Hit:4 http://security.ubuntu.com/ubuntu bionic-security InRelease
Reading package lists... Done

$ sudo apt-get install \
>     apt-transport-https \
>     ca-certificates \
>     curl \
>     software-properties-common
Reading package lists... Done
Building dependency tree       
Reading state information... Done
ca-certificates is already the newest version (20180409).
curl is already the newest version (7.58.0-2ubuntu3).
software-properties-common is already the newest version (0.96.24.32.1).
The following NEW packages will be installed
  apt-transport-https
0 to upgrade, 1 to newly install, 0 to remove and 0 not to upgrade.
Need to get 1,692 B of archives.
After this operation, 152 kB of additional disk space will be used.
Do you want to continue? [Y/n] 
Get:1 http://gb.archive.ubuntu.com/ubuntu bionic/universe amd64 apt-transport-https all 1.6.1 [1,692 B]
Fetched 1,692 B in 0s (65.4 kB/s)               
Selecting previously unselected package apt-transport-https.
(Reading database ... 116694 files and directories currently installed.)
Preparing to unpack .../apt-transport-https_1.6.1_all.deb ...
Unpacking apt-transport-https (1.6.1) ...
Setting up apt-transport-https (1.6.1) ...

$ curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
OK

$ sudo apt-key fingerprint 0EBFCD88
pub   rsa4096 2017-02-22 [SCEA]
      9DC8 5822 9FC7 DD38 854A  E2D8 8D81 803C 0EBF CD88
uid           [ unknown] Docker Release (CE deb) <docker@docker.com>
sub   rsa4096 2017-02-22 [S]

$ sudo add-apt-repository \
>    "deb [arch=amd64] https://download.docker.com/linux/ubuntu \
>    $(lsb_release -cs) \
>    stable"
Hit:1 http://gb.archive.ubuntu.com/ubuntu bionic InRelease
Hit:2 http://gb.archive.ubuntu.com/ubuntu bionic-updates InRelease                                                                                    
Hit:3 http://gb.archive.ubuntu.com/ubuntu bionic-backports InRelease                                                                                  
Get:4 https://download.docker.com/linux/ubuntu bionic InRelease [64.4 kB]                                                       
Hit:5 http://security.ubuntu.com/ubuntu bionic-security InRelease                                                               
Fetched 64.4 kB in 0s (141 kB/s)
Reading package lists... Done

robin@xps:~/git/snapcraft.io$ sudo apt-get update
Hit:1 http://gb.archive.ubuntu.com/ubuntu bionic InRelease
Hit:2 http://gb.archive.ubuntu.com/ubuntu bionic-updates InRelease                                      
Hit:3 http://gb.archive.ubuntu.com/ubuntu bionic-backports InRelease                                                                                   
Hit:4 https://download.docker.com/linux/ubuntu bionic InRelease                                                                                        
Hit:5 http://security.ubuntu.com/ubuntu bionic-security InRelease                                                                
Reading package lists... Done  

$ sudo apt-get install docker-ce
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Package docker-ce is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source

E: Package 'docker-ce' has no installation candidate

J'ai d'abord pensé que Docker n'avait pas encore publié de paquet pour Bionic (c'est très récent), mais lorsque j'ai cherché " install docker-ce ubuntu 18.04 ", j'ai trouvé un guide qui semble spécifique à la version 18.04 et qui donne exactement les mêmes instructions, ce qui suggère que cela a au moins fonctionné pour l'auteur :

https://linuxconfig.org/how-to-install-docker-on-ubuntu-18-04-bionic-beaver

Quelqu'un a-t-il une idée de la raison pour laquelle cela ne fonctionne pas pour moi ?