Issue with cache under Simpletest

Hi, I have been using your module as part of a suite under Simpletest, and I have encountered some weird errors in cache processing, as reported here. I don't think the problem is yours but it manifests as a failure to unserialize the data. When seeking a workaround, I found that suppressing the notice as follows meant that all my tests succeeded:

<?php
    if ($cache->serialized) {
      $cache->data = @unserialize($cache->data);
    }
?>

This change is harmless as far as I can see so I'd ask you to consider it as without it there are puzzling test failures.