root@server:~#  attic change-passphrase -v /mnt/backups/my-backup.attic
Enter passphrase for /mnt/backups/my-backup.attic:
Traceback (most recent call last):
  File "/usr/bin/attic", line 3, in <module>
    main()
  File "/usr/lib/python3/dist-packages/attic/archiver.py", line 715, in main
    exit_code = archiver.run(sys.argv[1:])
  File "/usr/lib/python3/dist-packages/attic/archiver.py", line 705, in run
    return args.func(args)
  File "/usr/lib/python3/dist-packages/attic/archiver.py", line 92, in do_change_passphrase
    key.change_passphrase()
AttributeError: 'PassphraseKey' object has no attribute 'change_passphrase'
root@server:~#