Unpleasant warning

Created by: tiagofrepereira2012

This package is raising this unpleasant warning every time that you run ./bin/bob_dbmanage.py --help

bob.db.biosecure.test.test_driver_api ... /idiap/group/torch5spro/conda/envs/bob-2.2.0-py27_0/lib/python2.7/site-packages/sqlalchemy/sql/default_comparator.py:153: SAWarning: The IN-predicate on "client.sgroup" was invoked with an empty sequence. This results in a contradiction, which nonetheless can be expensive to evaluate.  Consider alternative strategies for improved performance.
  'strategies for improved performance.' % expr)