title: What is this Magento open_basedir issue all about?
body: <p>Running Magento with multiple stores. The base store works perfectly. On the secondary store when reaching checkout and the switch to https this set of warnings is generated: </p>
  
  <pre><code>Warning: require_once() [function.require-once]: open_basedir restriction in effect.     
  
  File(/var/www/vhosts/mainstore.com/httpdocs/app/Mage.php) is not within the allowed path(s): (/var/www/vhosts/secondarystore.com/httpdocs:/tmp) in /var/www/vhosts/secondarystore.com/httpdocs/index.php on line 41
  
  Warning: require_once(/var/www/vhosts/mainstore.com/httpdocs/app/Mage.php) [function.require-once]: failed to open stream: Operation not permitted in /var/www/vhosts/secondarystore.com/httpdocs/index.php on line 41
  
  Fatal error: require_once() [function.require]: Failed opening required '/var/www/vhosts/mainstore.com/httpdocs/app/Mage.php' (include_path='.:') in /var/www/vhosts/secondarystore.com/httpdocs/index.php on line 41
  </code></pre>
  
  <p>phpinfo shows the following for open_basedir </p>
  
  <pre><code>local value : /var/www/vhosts/mainstore.com/httpdocs:/tmp
  master value: none
  </code></pre>
  
  <p>What gives? </p>