maas package missing dependency on python-decorator

As seen here: http://d-jenkins.ubuntu-ci:8080/view/MAAS/job/utopic-adt-maas/74/console

Setting up maas-dns (1.6+bzr2367+2423+279-0ubuntu1) ...
Traceback (most recent call last):
  File "/usr/bin/django-admin", line 5, in <module>
    management.execute_from_command_line()
  File "/usr/lib/python2.7/dist-packages/django/core/management/__init__.py", line 399, in execute_from_command_line
    utility.execute()
  File "/usr/lib/python2.7/dist-packages/django/core/management/__init__.py", line 392, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/usr/lib/python2.7/dist-packages/django/core/management/base.py", line 242, in run_from_argv
    self.execute(*args, **options.__dict__)
  File "/usr/lib/python2.7/dist-packages/django/core/management/base.py", line 284, in execute
    self.validate()
  File "/usr/lib/python2.7/dist-packages/django/core/management/base.py", line 310, in validate
    num_errors = get_validation_errors(s, app)
  File "/usr/lib/python2.7/dist-packages/django/core/management/validation.py", line 34, in get_validation_errors
    for (app_name, error) in get_app_errors().items():
  File "/usr/lib/python2.7/dist-packages/django/db/models/loading.py", line 196, in get_app_errors
    self._populate()
  File "/usr/lib/python2.7/dist-packages/django/db/models/loading.py", line 78, in _populate
    self.load_app(app_name)
  File "/usr/lib/python2.7/dist-packages/django/db/models/loading.py", line 99, in load_app
    models = import_module('%s.models' % app_name)
  File "/usr/lib/python2.7/dist-packages/django/utils/importlib.py", line 40, in import_module
    __import__(name)
  File "/usr/lib/python2.7/dist-packages/maasserver/models/__init__.py", line 46, in <module>
    from maasserver.models.bootimage import BootImage
  File "/usr/lib/python2.7/dist-packages/maasserver/models/bootimage.py", line 26, in <module>
    from maasserver.models.nodegroup import NodeGroup
  File "/usr/lib/python2.7/dist-packages/maasserver/models/nodegroup.py", line 37, in <module>
    from maasserver.refresh_worker import refresh_worker
  File "/usr/lib/python2.7/dist-packages/maasserver/refresh_worker.py", line 20, in <module>
    from maasserver.models.user import get_creds_tuple
  File "/usr/lib/python2.7/dist-packages/maasserver/models/user.py", line 25, in <module>
    from piston.models import (
  File "/usr/lib/python2.7/dist-packages/piston/models.py", line 11, in <module>
    from signals import consumer_post_save, consumer_post_delete
  File "/usr/lib/python2.7/dist-packages/piston/signals.py", line 5, in <module>
    from utils import send_consumer_mail
  File "/usr/lib/python2.7/dist-packages/piston/utils.py", line 13, in <module>
    from decorator import decorator
ImportError: No module named decorator
Setting up maas-region-controller (1.6+bzr2367+2423+279-0ubuntu1) ...