archive-wal fails due to reporting glitch

[Stuart Bishop]

Traceback (most recent call last):
  File "/usr/bin/swiftwal", line 9, in <module>
    load_entry_point('swiftwal==0.2.0', 'console_scripts', 'swiftwal')()
  File "/usr/lib/python2.7/dist-packages/swiftwal/commands.py", line 746, in main
    args.func(args)
  File "/usr/lib/python2.7/dist-packages/swiftwal/commands.py", line 371, in archive_wal_command
    prate(start_time, time.time(), wal_size)))
  File "/usr/lib/python2.7/dist-packages/swiftwal/commands.py", line 77, in prate
    return '{0} B/s '.format(ps.rtrim())
AttributeError: 'str' object has no attribute 'rtrim'

[Stuart Bishop (stub)]

Workaround, don't use --verbose