When a svn repository is successfully deleted, an error message is appended to svn log.
In SVN/Repository/Destructor.php :
if (! $this->dao->delete($repository->getId())) {
$this->logger->error('Unable to delete repository:' . $repository->getName() . ' from database');
} else {
$this->logger->error('Repository:' . $repository->getName() . ' deleted from database with success');
}