Do I need to add `TEST_IMAGE` and `HEAD_IMAGE` to the CI/CD variables?

Hello,

My last pipeline failed with:

$ docker pull $HEAD_IMAGE || true
# invalid reference format
$ docker build --cache-from $HEAD_IMAGE --tag $TEST_IMAGE .
# invalid argument "index.docker.io//complete-linux:cd09f898" for "-t, --tag" flag: invalid reference format
# See 'docker build --help'.

I had last issue: https://github.com/christian-korneck/docker-pushrm/issues/20. And I searched “gitlab docker pushrm” and found your repository. I copied all files and modified them.