title: How do I check if an image:tag exists in gitlab container registry
body: <p>I know that this can be done with <code>dockerhub</code>. I want to know if there is something similar available for gitlab registry. </p>
  
  <p>The use case is that, I have written a fabric script to revert a deployment to a particular tag provided by the user. Before actually pulling in the images, I want to know whether an image with the specified tag exists in the registry and warn the user accordingly.</p>
  
  <p>I've searched in their documentation, but couldn't find anything.</p>
  
  <p>Note: User here is the person who is deploying the code.</p>