This package needs some serious testing, from what I see dbconfig-common is broken.  Not only is dbconfig-common configuration skipped on initial installation, dpkg-reconfigure doesn't even work.

---
$ sudo dpkg-reconfigure keystone
keystone stop/waiting
dbconfig-common: writing config to /etc/dbconfig-common/keystone.conf
Replacing config file /etc/dbconfig-common/keystone.conf with new version
creating database keystone.db: success.
verifying database keystone.db exists: success.
Traceback (most recent call last):
  File "/usr/bin/keystone-manage", line 28, in <module>
    cli.main(argv=sys.argv, config_files=config_files)
  File "/usr/lib/python2.7/dist-packages/keystone/cli.py", line 148, in main
    return run(cmd, (args[:1] + args[2:]))
  File "/usr/lib/python2.7/dist-packages/keystone/cli.py", line 134, in run
    return CMDS[cmd](argv=args).run()
  File "/usr/lib/python2.7/dist-packages/keystone/cli.py", line 36, in run
    return self.main()
  File "/usr/lib/python2.7/dist-packages/keystone/cli.py", line 57, in main
    driver.db_sync()
  File "/usr/lib/python2.7/dist-packages/keystone/identity/backends/sql.py", line 135, in db_sync
    migration.db_sync()
  File "/usr/lib/python2.7/dist-packages/keystone/common/sql/migration.py", line 50, in db_sync
    current_version = db_version()
  File "/usr/lib/python2.7/dist-packages/keystone/common/sql/migration.py", line 66, in db_version
    return db_version_control(0)
  File "/usr/lib/python2.7/dist-packages/keystone/common/sql/migration.py", line 72, in db_version_control
    CONF.sql.connection, repo_path, version)
  File "<string>", line 2, in version_control
  File "/usr/lib/python2.7/dist-packages/migrate/versioning/util/__init__.py", line 159, in with_engine
    return f(*a, **kw)
  File "/usr/lib/python2.7/dist-packages/migrate/versioning/api.py", line 250, in version_control
    ControlledSchema.create(engine, repository, version)
  File "/usr/lib/python2.7/dist-packages/migrate/versioning/schema.py", line 139, in create
    table = cls._create_table_version(engine, repository, version)
  File "/usr/lib/python2.7/dist-packages/migrate/versioning/schema.py", line 180, in _create_table_version
    if not table.exists():
  File "/usr/lib/python2.7/dist-packages/sqlalchemy/schema.py", line 549, in exists
    self.name, schema=self.schema)
  File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 2274, in run_callable
    conn = self.contextual_connect()
  File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 2340, in contextual_connect
    self.pool.connect(), 
  File "/usr/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 210, in connect
    return _ConnectionFairy(self).checkout()
  File "/usr/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 371, in __init__
    rec = self._connection_record = pool._do_get()
  File "/usr/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 758, in _do_get
    return self._create_connection()
  File "/usr/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 174, in _create_connection
    return _ConnectionRecord(self)
  File "/usr/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 256, in __init__
    self.connection = self.__connect()
  File "/usr/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 316, in __connect
    connection = self.__pool._creator()
  File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/strategies.py", line 80, in connect
    return dialect.connect(*cargs, **cparams)
  File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/default.py", line 280, in connect
    return self.dbapi.connect(*cargs, **cparams)
sqlalchemy.exc.OperationalError: (OperationalError) unable to open database file None None