title: Rails Date#strptime parsing dates incorrectly before year 200
body: <p>Why does Rails' <code>Date#strptime</code> parse "13/08" as August 15 or August 14 before the year 200?</p>
  
  <pre><code>Date.strptime('13/08/99', '%d/%m/%Y')  #=&gt; Thu, 15 Aug 0099
  Date.strptime('13/08/100', '%d/%m/%Y') #=&gt; Fri, 14 Aug 0100
  Date.strptime('13/08/199', '%d/%m/%Y') #=&gt; Tue, 14 Aug 0199
  Date.strptime('13/08/200', '%d/%m/%Y') #=&gt; Wed, 13 Aug 0200
  </code></pre>