include Oracle "not connected" check

Oracle error message looks like this:

    OperationalError: ORA-03114: not connected to ORACLE

Author: dlamotte

djcelery/loaders.py

@@ -68,7 +68,8 @@ def _close_database(self):
             try:
                 close()
             except DATABASE_ERRORS, exc:
-                if "closed" not in str(exc):
+                str_exc = str(exc)
+                if "closed" not in str_exc and "not connected" in str_exc:
                     raise
 
     def close_database(self, **kwargs):