SET_AUDIT_TRAIL_LOCATION tablespace move & capacity calculation

This seems to calculate if there is space for the audit trail based on the current tablespace size rather than max size.

Calculated total size of aud$ based on extents = 3107 M

create tablespace "AUDIT_TBS"  SIZE  3150M AUTOEXTEND ON NEXT 10240K MAXSIZE 4096M ;

BEGIN
 DBMS_AUDIT_MGMT.SET_AUDIT_TRAIL_LOCATION(
audit_trail_type => DBMS_AUDIT_MGMT.AUDIT_TRAIL_AUD_STD,
  audit_trail_location_value => 'AUDIT_TBS');
END;
/

ORA-46267: Insufficient space in 'AUDIT_TBS' tablespace, cannot complete operation

Alter datafile  set size = 3500M, MaxSize = 4596.

Rerun set audit trail location.

Final AUDIT_TBS tablespace:
Size: 3500M, Used: 3073M

This is expected behaviour, see comment on:
http://oraclesqltips.blogspot.com.au/2013/09/ora-46267-insufficient-space-in-sysaux.html