def repo_name_list(self):
        p = self.layout.repository_config_dir
        return [r for r in os.listdir(p) if r != 'README']
Test that FileField.save_form_data considers None to mean "no change"
dataset/ETHPy150Open bloomberg/phabricator-tools/py/abd/abdt_fs.py/Accessor.repo_name_list--crossover with--dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-1.5/tests/regressiontests/model_fields/tests.py/FileFieldTests.test_unchanged