CONF.command.cmd_class.main()\n  File "/usr/lib/python2.6/site-packages/keystone/cli.py", line 67, in main\n    driver.db_sync(CONF.command.version)\n  File "/usr/lib/python2.6/site-packages/keystone/identity/backends/sql.py", line 142, in db_sync\n    migration.db_sync(version=version)\n  File "/usr/lib/python2.6/site-packages/keystone/common/sql/migration.py", line 52, in db_sync\n    return versioning_api.upgrade(CONF.sql.connection, repo_path, version)\n  File "/usr/lib/python2.6/site-packages/migrate/versioning/api.py", line 186, in upgrade\n    return _migrate(url, repository, version, upgrade=True, err=err, **opts)\n  File "<string>", line 2, in _migrate\n  File "/usr/lib/python2.6/site-packages/migrate/versioning/util/__init__.py", line 159, in with_engine\n    return f(*a, **kw)\n  File "/usr/lib/python2.6/site-packages/migrate/versioning/api.py", line 366, in _migrate\n    schema.runchange(ver, change, changeset.step)\n  File "/usr/lib/python2.6/site-packages/migrate/versioning/schema.py", line 91, in runchange\n    change.run(self.engine, step)\n  File "/usr/lib/python2.6/site-packages/migrate/versioning/script/py.py", line 145, in run\n    script_func(engine)\n  File "/usr/lib/python2.6/site-packages/keystone/common/sql/migrate_repo/versions/023_drop_credential_constraints.py", line 43, in upgrade\n    migration_helpers.remove_constraints(list_constraints(migrate_engine))\n  File "/usr/lib/python2.6/site-packages/keystone/common/sql/migration_helpers.py", line 50, in remove_constraints\n    constraint_def[\'fk_column\']))).drop()\n  File "/usr/lib/python2.6/site-packages/keystone/common/sql/migration_helpers.py", line 30, in get_fkey_constraint_name\n    constraint_name = fkeys[0].name\nIndexError: list index out of range\n'