title: Cannot setup tracking information; starting point 'origin/master' is not a branch
body: <p>Can someone explain why this isn't working?</p>
  
  <pre><code>➜  workspace git:(REL-BRANCH-1.0.1d) ✗ git branch -a
    REL-BRANCH-1.0.1c
  * REL-BRANCH-1.0.1d
    remotes/origin/REL-BRANCH-1.0.1c
    remotes/origin/master
  ➜  workspace git:(REL-BRANCH-1.0.1d) ✗ git checkout -t origin/master 
  fatal: Cannot setup tracking information; starting point 'origin/master' is not a branch.
  ➜  workspace git:(REL-BRANCH-1.0.1d) ✗ git checkout -t remotes/origin/master
  fatal: Cannot setup tracking information; starting point 'remotes/origin/master' is not a branch.
  </code></pre>