Database get's deleted if an upgrade fails

When upgrading ISPConfig from < 3.0.3 there is a full db update. The update script creates a backup of the current database, but it gets saved in the install/ dir, which is deleted right after update.php has run. If update.php fails, the db is deleted, install/ as well, and you now have a server without dbispconfig database .. AND NO BACKUP!

Let's move the existing_db.sql out of the install dir?