another dbua issue

As another part of the same project I'm dealing with in Std Ed upgrade 11.2.0.2 to 11.2.0.4

Here's the over-all process flow

1 - create/refresh a test database with rman duplicate from active database (another test db).   (this part works fine)

2 - upgrade the new database from 11.2.0.2 to 11.2.0.4.  This works fine (with the caveats mentioned in the previous thread)

3 - Again, refresh via rman active duplicate.  Same source and target db as before.

   - stop the target (rman auxiliary) database.

   - delete all data, control, and redo files, leaving only the spfile that was left over in the 11.2.0.2 home.

   - modify /etc/oratab to point back to the 11.2.0.2 home