nikola bootswatch_theme python 3.x

[sluckxz]

$ nikola bootswatch_theme -n swatch_cerulean -s cerulean -p bootstrap
WARNING: The post_compilers option is deprecated, use COMPILERS instead.
Creating 'swatch_cerulean' theme from 'cerulean' and 'bootstrap'
Downloading:  http://bootswatch.com/2/cerulean/bootstrap.min.css

Traceback (most recent call last):
  File "/home/default/nikola.virtenv/lib/python3.3/site-packages/doit/doit_cmd.py", line 103, in run
    return self.sub_cmds[command].parse_execute(args)
  File "/home/default/nikola.virtenv/lib/python3.3/site-packages/doit/cmd_base.py", line 60, in parse_execute
    return self.execute(params, args)
  File "/home/default/nikola.virtenv/lib/python3.3/site-packages/nikola/plugin_categories.py", line 72, in execute
    self._execute(options, args)
  File "/home/default/nikola.virtenv/lib/python3.3/site-packages/nikola/plugins/command/bootswatch_theme.py", line 102, in _execute
    output.write(data)
TypeError: 'str' does not support the buffer interface