title: mod_rewrite not working with directory names
body: <p>I am using mod_rewrite to pass identifiers to my web app in the form:</p>
  
  <pre><code>http://clipi.ca/1W
  </code></pre>
  
  <p>I am identifying these with a simple regex:</p>
  
  <pre><code>RewriteCond %{REQUEST_URI} ^/([0-9a-zA-Z]+)$
  RewriteRule ^(.*)$ /index.php?urlid=%1 [L,QSA]
  </code></pre>
  
  <p>...which works fine in most cases. However I noticed that when the identifier is the name of a directory, the rewrite is failing and Apache is returning a directory index!</p>
  
  <p>How can I stop this behavior and have the rewrite rule apply to directories as well? (Note that as soon as an actual file inside a directory is referenced, the rewrite condition fails and it is not a problem.)</p>