title: Docker pull fails with "Tag latest not found in repository" even when "latest" tag exists
body: <p>I tried to pull the Fedora docker image using the following command but it failed with <code>Tag latest not found in repository docker.io/library/fedora</code> error:</p>
  
  <pre><code># docker pull fedora
  Using default tag: latest
  latest: Pulling from library/fedora
  62b0615068df: Pull complete 
  cd1e9127a3f8: Verifying Checksum 
  Pulling repository docker.io/library/fedora
  Tag latest not found in repository docker.io/library/fedora
  </code></pre>
  
  <p>However, it succeeded when I pulled it with the <code>latest</code> tag explicitly specified.</p>
  
  <pre><code>docker pull fedora:latest
  latest: Pulling from library/fedora
  cd1e9127a3f8: Pull complete 
  Digest: sha256:52db7a1a18f173622a9b1a75354c7266220bffb7187c4880590805af0d7679d6
  Status: Downloaded newer image for fedora:latest
  </code></pre>
  
  <p>In an attempt to understand this further, I tried to pull the CentOS docker image. However, I did not see this behavior in case of CentOS:</p>
  
  <pre><code>docker pull centos
  Using default tag: latest
  latest: Pulling from library/centos
  Digest: sha256:1a62cd7c773dd5c6cf08e2e28596f6fcc99bd97e38c9b324163e0da90ed27562
  Status: Downloaded newer image for centos:latest
  </code></pre>
  
  <p><strong>Version Info</strong></p>
  
  <pre><code># cat /etc/redhat-release 
  Red Hat Enterprise Linux Server release 7.2 (Maipo)
  # docker -v
  Docker version 1.9.1, build a34a1d5
  </code></pre>
  
  <p>Can someone please help me understand this behavior?</p>