Influxdb restore of a single database in portable format not working

#1

Testing a database restore so backed up the database tickdata with “portable” format .

now in the same server I dropped the database tickdata and try to restore back into the same server first with portable switch and then with -online switch … does not work!
I am glad I checked this out before I upgraded to 1.5.2

    $ /usr/bin/influxd restore -portable -database tickdata  -rp autogen  /opt/influxdb/backups/backup_influx_dbs/08May2018/tickdata                        
 2018/05/11 11:26:05 error updating meta: DB metadata not changed. database may already exist
    restore: DB metadata not changed. database may already exist

Any help appreciated.

#2

the journal shows :
May 11 14:36:15 cricket influxd[11864]: 2018-05-11T19:36:15Z info database already exists {"service": "snapshot"}

updated the the nightly build ver ( 1.6 ) still not working! even after setting index

index-version = "tsi1"