Semi-manual helper image
It would be useful to define only the helper image Docker repository, letting the hash based tag be applied automatically.
This would be especially useful for PAAS runner because the helper image gets downloaded with each job (actual runner is never warm). We don't want to update the configuration with each version update, we don't want to hit Docker Hub rate limits either
Perhaps GitLab Runner already has something similar. Otherwise, it could be done easily with a new Heptapod PAAS Runner specific option.
Heptapod PAAS Runner already applies its tag version for the main image, but the hardcoded prefix point to registry.h.n (since the only implementation currently is Clever Runner, this is not a problem at this point, but can also be improved)