Merge "Remove unused imports in db package"

quantum/db/api.py

@@ -29,7 +29,7 @@ import sqlalchemy as sql
 from sqlalchemy import create_engine
 from sqlalchemy.exc import DisconnectionError
 from sqlalchemy.interfaces import PoolListener
-from sqlalchemy.orm import sessionmaker, exc
+from sqlalchemy.orm import sessionmaker
 
 from quantum.db import model_base
 from quantum.openstack.common import log as logging