title: git log strange behavior
body: <p>I just got pretty strange result that I can't explain</p>
  
  <p>I wanted to determine difference between two branches</p>
  
  <p>So i typed</p>
  
  <pre><code>git log master..release1
  </code></pre>
  
  <p>And I've got multiple commits, including let's say <strong>aa11bb22cc33</strong></p>
  
  <p>But then I called</p>
  
  <pre><code>git branch --contains aa11bb22cc33
  </code></pre>
  
  <p>And I've got</p>
  
  <pre><code>release1
  * master
  </code></pre>
  
  <p>How could this happen?!</p>
  
  <p>My git log command by definition should show only those commits that are reachable in release1, but not reachable in master?</p>
  
  <p>I also tried equivalent</p>
  
  <pre><code>git log ^master release1
  </code></pre>
  
  <p>with the same strange result.</p>
  
  <p>Please explain if you can how is that possible.</p>
  
  <p>P.S. git 1.8.0</p>