Invoke YAML loading trouble

invoke.yaml

deployments:
  testing:
    host: xyz.domain.tld
    user: username
    destination: /home/username/html/misc/path/
    sources:
      - index.html
      - img

tasks.py

# -*- coding: UTF-8 -*-

"""
A couple of `Invoke`_ **tasks** to…

.. _Invoke: http://www.pyinvoke.org/
"""

from __future__ import absolute_import
from __future__ import unicode_literals
from __future__ import print_function

from invoke import Collection, ctask as task

from corelib.tasks.utils import make_dirs as setup, remove_dirs as clean
from corelib.tasks.web import css_ns, js_ns
from corelib.tasks.deployment import deploy_ns


@task(pre=[setup], post=[clean])
def build(ctx):
  """
  Build an `index.html`.

  Using the templates in ``html/`` and the data in ``data/``.

  """
  print('Creating new `index.html`.')
  # …

# #########################################################################
# If I comment out the stuff below, the data from `invoke.yaml` is loaded #
# #########################################################################

namespace = Collection(css_ns, js_ns, deploy_ns)

namespace.add_task(build, default=True)

namespace.configure({
  'mk_dirs': ['.tmp/'],
  'rm_dirs': ['.tmp/', '.sass-cache/'],
  'sass_source_dir': 'html/',
  'sass_destination_dir': '.tmp/',
  'css_source_dir': 'html/',
  'css_destination_dir': '.tmp/',
  'default_deployment': 'testing'
})