title: Prevent rsync from deleting destination files that match a given pattern
body: <p>I'm using rsync to sync files from a source to a destination:</p>
  
  <pre><code>rsync -av --delete source destination
  </code></pre>
  
  <p>I have a single directory on the destination side which is not on the source side. I'd like to prevent rsync from deleting this directory. Is there an option I can pass to rsync to prevent this directory from being deleted upon sync?</p>