title: Does "The push refers to a repository" actually mean "…refers to a registry"?
body: <p>I'm reasonably familiar with Docker at this point but as these things go I'm no expert.</p>
  
  <p>When I do a <code>docker push</code>, I always (?) get what looks like an informative message: <code>The push refers to a repository [registry.bigco.com/foobar/blatz]</code>.</p>
  
  <p>Empirically it looks like if I use the command line tools, I will get this message if I do:</p>
  
  <pre><code>docker push registry.bigco.com/foobar/blatz
  </code></pre>
  
  <p>(In this case if I've got several <code>registry.bigco.com/foobar/blatz</code> images tagged with "colon tags" (e.g. <code>registry.bigco.com/foobar/blatz:development</code>) lying around in my local Docker environment, then this operation will <code>push</code> them all.)</p>
  
  <p>I'll also get it if I do:</p>
  
  <pre><code>docker push registry.bigco.com/foobar/blatz:development
  </code></pre>
  
  <p>…i.e. a specific tag.  That surprises me, because I figured the presence of the <code>development</code> "colon tag" picks out a very specific image I'm pushing, and not the contents of my local Docker environment, and, indeed, that's all that gets <code>push</code>ed.  That is, if I'm understanding what "repository" means in this case, I'm certainly trying <em>not</em> to refer to a repository at all!</p>
  
  <p>What <em>is</em> this message trying to tell me?  Is it trying, actually, to tell me that my <code>push</code> operation is referring to a <em>registry</em>, i.e. that the <code>registry.bigco.com</code> part is being treated as not a username on Docker Hub?  Is this a gigantic typo?</p>