title: Merging new `mod_rewrite` rules and preserving old behaviour, what is wrong?
body: <p>I am using Apache2 with the following (good) <code>.htaccess</code> at the root of my site,</p>
  
  <pre><code> #OLD (GOOD, IS WORKING!)
   # If requested url is an existing file or folder, don't touch it
   RewriteCond %{REQUEST_FILENAME} -d [OR]
   RewriteCond %{REQUEST_FILENAME} -f
   RewriteRule . - [L]
  
   RewriteRule ^(urn|URN):(.+)$     index.php?urn=$2 [L]
   RewriteRule ^([a-zA-Z\d\-]+)$    index.php?obj=$1 [L]
  </code></pre>
  
  <p>Now I need to merge a new condition for the folder xWiki</p>
  
  <pre><code>#NEW: some conflicts, how to preserve old and add /xWiki* behaviour?
  RewriteCond %{REQUEST_FILENAME} !-f  
  RewriteRule ^xWiki/?(.*)$ /xWiki/index.php?title=$1 [L,QSA]
  </code></pre>
  
  <p><strong>How to "merge" preserving old behaviour except to <code>/xWiki</code>?</strong></p>
  
  <p>Only adding the <code>RewriteRule ^xWiki/?(.*)$</code> not works, and the <code>!-f</code>  is in conflict with the same <code>-f</code> cond...</p>