title: fetch remote branch with the same name
body: <p>I want to fetch a branch from a remote, but my branch name does not start with remote name, for example:</p>
  
  <pre><code>git checkout -b BRANCH origin/BRANCH
  </code></pre>
  
  <p>It work in some cases, but in some cases I get this error:</p>
  
  <pre><code>fatal: git checkout: updating paths is incompatible with switching branches.
  </code></pre>
  
  <p>while i am sure that the remote has this branch, and this works:</p>
  
  <pre><code>git checkout -b origin/BRANCH
  </code></pre>
  
  <p>After that, I have to switch to another branch and rename branch origin/BRANCH to BRANCH, and then switch to BRANCH again...
  I want to know what that error means.</p>