This can actually lead to a weird behavior for users. In a system
having something under people.debian.org in apt sources.list and
apt-transport-https not installed, in today's testing upgrade,
$ sudo apt-get update
[...]
E: The method driver /usr/lib/apt/methods/https could not be found.
N: Is the package apt-transport-https installed?
$ sudo apt-get install apt-transport-https
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following NEW packages will be installed:
apt-transport-https
0 upgraded, 1 newly installed, 0 to remove and 275 not upgraded.
Need to get 132 kB of archives.
After this operation, 221 kB of additional disk space will be used.
WARNING: The following packages cannot be authenticated!
apt-transport-https
Install these packages without verification? [y/N]
E: Some packages could not be authenticated