title: string.LastIndexOf() Bug?
body: <p>does anyone know why:</p>
  
  <pre><code>"  &lt;exception&gt;".LastIndexOf("&lt;",0) returns -1 (wrong)
  </code></pre>
  
  <p>while</p>
  
  <pre><code>"  &lt;exception&gt;".LastIndexOf("&lt;") returns 2 (right)
  </code></pre>
  
  <p>and</p>
  
  <pre><code>"&lt;exception&gt;".LastIndexOf("&lt;",0) returns 0 (right)
  </code></pre>
  
  <p>Is this a bug or am I misunderstanding the LastIndexOf-Method?</p>