$ juju restore-backup -b --upload-tools --file juju-backup-20160316-110454.tar.gz 
ERROR old bootstrap instance ["maas19-node2.maas19:/MAAS/api/1.0/nodes/node-562d8f0c-d8e4-11e5-b0d8-525400c38f67/"] still seems to exist; will not replace
aim@spicy:~/juju (master) (local.maas)
$ juju restore-backup --upload-tools --file juju-backup-20160316-110454.tar.gz 
ERROR could not exit restoring status: cannot complete restore: <nil>: Restore did not finish succesfuly
ERROR cannot upload backup file: PUT https://10.17.20.215:17070/model/5dfa57a0-37ec-48eb-8aaf-b53b076176a3/backups: while storing backup archive: backup metadata "20160316-110454.5dfa57a0-37ec-48eb-8aaf-b53b076176a3" already exists