how to get a preview of what Github's pull request diff will look like
<p>How to do diff between branches to get what the Merge diff will look like</p>

<p>consider this graph</p>

<pre><code>*   master
|\
| * b1
|\ 
| * b2
</code></pre>

<p>if im on <code>b2</code>, and the person on <code>b1</code> beat me and merged into <code>master</code>, </p>

<p>if i do</p>

<blockquote>
  <p>project>b2 $ git diff origin/master</p>
</blockquote>

<p>the diff would include b1, which would not be included in the PR, how do I reproduce this in command line.</p>