Datafiles created during RMAN backup cause problems when restoring database

If a new file(s) was created during RMAN backup there will be problems with restore (I had
this problem with Oracle 8.1.7.x where 'set until time' in the restore script did not help.
Not sure if it's been fixed in later versions). To overcome this register database in a test
catalogue database and remove the file(s) that was created during the backup from dfatt
table.

1. Register database in test catalogue database or if the database already registered just
resync catalgue

2. Connect to test catalog from sqlplus and remove file(s) from dfatt table:

SQLPLUS> delete from dfatt where fname = 'PATH TO DATAFILE';

SQLPLUS> commit;

3. Start the restore as per standard procedure

4. When database has been restored use 

RENAME FILE AS

to rename the missing file(s)