title: PHP strtotime() is not returning the correct month
body: <p>Being that the current month/year is January 2012, why does the following code return December 2011 and not November 2011?</p>
  
  <pre><code>echo date("F Y", strtotime("-2 months"));
  </code></pre>
  
  <p>This is on PHP 5.3.0 if it makes a difference.</p>