Add log description to lib/db/upgrade.php block

Bug 1447377

Change-Id: Id0f64a6dc883f31de69595a05a321e2ec7ac1b09

htdocs/lib/db/upgrade.php

@@ -4067,6 +4067,7 @@ function xmldb_core_upgrade($oldversion=0) {
     }
 
     if ($oldversion < 2015042800) {
+        log_debug('Clear Dwoo cache of unescaped institution names');
         require_once(get_config('libroot').'dwoo/dwoo/Dwoo/Core.php');
         @unlink(get_config('dataroot') . 'dwoo/compile/default' . get_config('docroot') . 'theme/raw/' . 'templates/view/accesslistrow.tpl.d'.Dwoo_Core::RELEASE_TAG.'.php');
         @unlink(get_config('dataroot') . 'dwoo/compile/default' . get_config('docroot') . 'theme/raw/' . 'templates/admin/users/accesslistitem.tpl.d'.Dwoo_Core::RELEASE_TAG.'.php');