BioDatabase method training_files causes tests to fail

BioDatabase method training_files causes bob.db.biowave_test tests to fail, because bob.db.biowave_test doesn't have group world. Error is rised while executing line - https://gitlab.idiap.ch/bob/bob.bio.base/blob/master/bob/bio/base/database/database.py#L485 :

files = self.sort(self.objects(protocol=self.protocol, groups='world', **training_options))

The complete error message:

ERROR: bob.bio.vein.tests.test_databases.test_biowave_test
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/idiap/group/torch5spro/conda/envs/bob-2.3.4-py27_0/lib/python2.7/site-packages/nose/case.py", line 197, in runTest
    self.test(*self.arg)
  File "/remote/idiap.svm/home.active/teglitis/Desktop/BOB/BOB-VEIN/src/bob.bio.base/bob/bio/base/test/utils.py", line 75, in wrapper
    return test(*args, **kwargs)
  File "/idiap/home/teglitis/Desktop/BOB/BOB-VEIN/src/bob.bio.vein/bob/bio/vein/tests/test_databases.py", line 51, in test_biowave_test
    check_database(database, protocol='all', groups=('dev', 'eval'))
  File "/remote/idiap.svm/home.active/teglitis/Desktop/BOB/BOB-VEIN/src/bob.bio.base/bob/bio/base/test/test_database_implementations.py", line 26, in check_database
    assert len(database.training_files('train_extractor')) > 0
  File "/remote/idiap.svm/home.active/teglitis/Desktop/BOB/BOB-VEIN/src/bob.bio.base/bob/bio/base/database/database.py", line 485, in training_files
    files = self.sort(self.objects(protocol=self.protocol, groups='world', **training_options))
  File "/idiap/home/teglitis/Desktop/BOB/BOB-VEIN/src/bob.bio.vein/bob/bio/vein/database/biowave_test.py", line 47, in objects
    retval = self.__db.objects(protocol=protocol, groups=groups, purposes=purposes, model_ids=model_ids)
  File "/remote/idiap.svm/home.active/teglitis/Desktop/BOB/BOB-VEIN/src/bob.db.biowave_test/bob/db/biowave_test/query.py", line 270, in objects
    groups = self.check_parameters_for_validity(groups, "group", self.groups())
  File "/remote/idiap.svm/home.active/teglitis/Desktop/BOB/BOB-VEIN/src/bob.db.base/bob/db/base/database.py", line 64, in check_parameters_for_validity
    raise ValueError("Invalid %s '%s'. Valid values are %s, or lists/tuples of those" % (parameter_description, parameter, valid_parameters))
ValueError: Invalid group 'world'. Valid values are ('dev', 'eval'), or lists/tuples of those

Is there some work-around to this?