title: Airflow on Kubernetes: couldn't parse image reference
body: <p>Running Airflow in GKE.
  When scheduler spawn workers I am facing the next problem:</p>
  <pre><code>Failed to apply default image tag &quot;my_registry_address_without_https:python:3.9.4-alpine&quot;: couldn't parse image reference &quot;my_registry_address_without_https:python:3.9.4-alpine&quot;: invalid reference format
  </code></pre>
  <p>In <code>airflow.cfg</code> I have the next configs:</p>
  <pre><code># The repository of the Kubernetes Image for the Worker to Run
  worker_container_repository = my_registry_address_without_https
  
  # The tag of the Kubernetes Image for the Worker to Run
  worker_container_tag = python:3.9.4-alpine
  </code></pre>
  <p>It supposes to parse properly, but can't understand, what am I missing..</p>