cleanat does not drop TDDL table

After executing cleanat, one DTM table TDDL still exists.

[trafodion@openstack-1 ~]$ cleanat
SQ environment is not up. Please issue 'sqstop abrupt' or 'ckillall' to kill any orphan processes.
Java HotSpot(TM) 64-Bit Server VM warning: Using incremental CMS is deprecated and will likely be removed in a future release
17/05/26 12:32:29 INFO Configuration.deprecation: hadoop.native.lib is deprecated. Instead, use io.native.lib.available
HBase Shell; enter 'help<RETURN>' for list of supported commands.
Type "exit<RETURN>" to leave the HBase Shell
Version 1.2.0-cdh5.7.1, rUnknown, Wed Jun 1 16:30:06 PDT 2016

disable_all 'TRAFODION.DTM.TLOG.*'
TRAFODION.DTM.TLOG0
TRAFODION.DTM.TLOG0_CONTROL_POINT
TRAFODION.DTM.TLOG1
TRAFODION.DTM.TLOG1_CONTROL_POINT

Disable the above 4 tables (y/n)?
4 tables successfully disabled

drop_all 'TRAFODION.DTM.TLOG.*'
TRAFODION.DTM.TLOG0
TRAFODION.DTM.TLOG0_CONTROL_POINT
TRAFODION.DTM.TLOG1
TRAFODION.DTM.TLOG1_CONTROL_POINT

Drop the above 4 tables (y/n)?
4 tables successfully dropped

hbase(main):042:0* list 'TRAFODION.*'
TABLE
TRAFODION.DTM.TDDL
1 row(s) in 0.0070 seconds

=> ["TRAFODION._DTM_.TDDL"]