title: Add exclude to existing yum repo configuration with puppet
body: <p>I'm using puppet for managing configuration a bunch of CentOS 5 servers. I would like to add a some package exclusions to the CentOS base yum repo configuration. Is there a way to do this with puppet?</p>
  
  <p>I am going to use the remi repo version of some packages and want to exclude the base versions from yum. To enable remi I have a <code>yumrepo</code> resource defined.</p>