Comment 8 for bug 1257021

Since https://github.com/openstack/trove/blob/master/trove/guestagent/datastore/mysql/service.py#L387 only logs an informative log in guestagent log, this is not doing any good to resolve the problem.
After handling the exception code shifts to https://github.com/openstack/trove/blob/master/trove/guestagent/datastore/mysql/service.py#L390 and permissions for mysql or rather "ignore_dbs" are still granted.

The fix would be to raise the exception instead of an informative logging.