title: Android repo command and switching branches
body: <p>I feel I have a pretty good understanding of git, but when it comes to the repo command, I get lost.  I've read about the repo command, but I'm still not sure how it ties everything together.</p>
  
  <p>My biggest question is can I change my current branches from gingerbread to ICS and possibly back?</p>
  
  <p>I see the command:</p>
  
  <pre><code>repo init -u https://android.googlesource.com/platform/manifest
  </code></pre>
  
  <p>From my understanding, this will create a repo with the master branch.  If I want to specify the branch, I can do:</p>
  
  <pre><code>repo init -u https://android.googlesource.com/platform/manifest -b android-4.0.1_r1
  </code></pre>
  
  <p>The download is about 8GB, I believe, so I don't want to have to blow my repo away if they share code.  is there a way to switch branches in repo?</p>