Cannot import nova.db.sqlalchemy.models

I am following up from bug #654584 as advised by soren I am launching the auth server with :

python /usr/bin/nova-api --flagfile=/etc/nova/nova-api.conf --nodaemonize --FAKE_subdomain=ec2 --verbose start

which does not show me the 404 not found anymore but I am getting different error now :

[.....]

  File "/usr/lib/pymodules/python2.6/nova/api/ec2/__init__.py", line 75, in __call__
    req.path)
  File "/usr/lib/pymodules/python2.6/nova/auth/manager.py", line 261, in authenticate
    user = self.get_user_from_access_key(access_key)
  File "/usr/lib/pymodules/python2.6/nova/auth/manager.py", line 581, in get_user_from_access_key
    user_dict = drv.get_user_from_access_key(access_key)
  File "/usr/lib/pymodules/python2.6/nova/auth/dbdriver.py", line 53, in get_user_from_access_key
    return self._db_user_to_auth_user(db.user_get_by_access_key({}, access))
  File "/usr/lib/pymodules/python2.6/nova/db/api.py", line 585, in user_get_by_access_key
    return IMPL.user_get_by_access_key(context, access_key)
  File "/usr/lib/pymodules/python2.6/nova/utils.py", line 203, in __getattr__
    backend = self.__get_backend()
  File "/usr/lib/pymodules/python2.6/nova/utils.py", line 198, in __get_backend
    self.__backend = __import__(name, None, None, fromlist)
  File "/usr/lib/pymodules/python2.6/nova/db/sqlalchemy/__init__.py", line 22, in <module>
    from nova.db.sqlalchemy import models
ImportError: cannot import name models

The full log is here :

http://is.gd/fNPB9

The command is :

euca-register mybucket/vmlinuz-2.6.32-23-server.manifest.xml

Let me know if you need more information.

Chmouel.