CI_PROJECT_NAME not being expanded

Summary

CI_PROJECT_NAME isn't expanded and this broke during my upgrade from 11.4 to 11.7 (I think I was running 11.4)

Steps to reproduce

use CI_PROJECT_NAME in a variable and it's not expanded.

# .gitlab-ci.yml

variables:
  docker_registry: docker-registry.example.com
  docker_image: group/${CI_PROJECT_NAME}
  tag: ${docker_registry}/${docker_image}:${CI_COMMIT_SHORT_SHA}

$ docker build --pull -t ${tag} -f Dockerfile .
invalid argument "docker-registry.example.com/group/${CI_PROJECT_NAME}:9e5cf45d" for "-t, --tag" flag: invalid reference format: repository name 

Example Project

git@gitlab.com:kneufeld/example1.git

What is the current bug behavior?

prints out building and pushing tag docker-registry.example.com/artsman/{CI_PROJECT_NAME}:589ba03c

What is the expected correct behavior?

prints out building and pushing tag docker-registry.example.com/artsman/example1:589ba03c

Relevant logs and/or screenshots

see output of: https://gitlab.com/kneufeld/example1/-/jobs/153900322

Output of checks

This bug happens on GitLab.com

Results of GitLab environment info

Expand for output related to GitLab environment info

(For installations with omnibus-gitlab package run and paste the output of:
sudo gitlab-rake gitlab:env:info)
(For installations from source run and paste the output of:
sudo -u git -H bundle exec rake gitlab:env:info RAILS_ENV=production)

Results of GitLab application Check

Expand for output related to the GitLab application check

(For installations with omnibus-gitlab package run and paste the output of:
sudo gitlab-rake gitlab:check SANITIZE=true)
(For installations from source run and paste the output of:
sudo -u git -H bundle exec rake gitlab:check RAILS_ENV=production SANITIZE=true)
(we will only investigate if the tests are passing)

Possible fixes

(If you can, link to the line of code that might be responsible for the problem)