title: git: empty arguments in post-receive hook
body: <p>I'm writing post-receive hook basing on the <code>post-receive-email</code> script from the <code>contrib</code> dir, but it seems that the <code>oldrev</code> and <code>newrev</code> arguments are empty.</p>
  
  <p>The script looks like this:</p>
  
  <pre><code>#!/bin/bash
  
  oldrev=$(git rev-parse $1)
  newrev=$(git rev-parse $2)
  </code></pre>
  
  <p>The script runs on push, but all <code>$1</code>, <code>$2</code>, <code>$oldrev</code> and <code>$newrev</code> are empty. Should I configure something to get it running?</p>
  
  <p>(The repository was created by <code>gitolite</code> if it does matter)</p>