title: Error on branch creation: "warning: refname 'master' is ambiguous."
body: <p>I've had simple project being managed in a Git repository. To date I haven't intentionally created any branches, but when I tried to create my first today using</p>
  
  <pre><code>$ git branch mybranch
  </code></pre>
  
  <p>I see this error:</p>
  
  <pre><code>warning: refname 'master' is ambiguous.
  fatal: Ambiguous object name: 'master'.
  </code></pre>
  
  <p>Digging deeper:</p>
  
  <pre><code>$ git branch -a          
  * master
  remotes/master/HEAD -&gt; master/master
  remotes/master/master
  </code></pre>
  
  <p>Is this normal to see in Git? Have I cloned my repository incorrectly? What is the best way to resolve this problem?</p>