Ubuntu 14.04 cloud config apt_sources error

No matter what I do I cannot get a custom apt_sources in cloud config to work. If I just add something like:

apt_sources:
 - source: "ppa:smoser/ppa"

I get the following in the cloud-init.log:

Dec 21 00:32:31 ubuntu1404x64 [CLOUDINIT] cc_apt_configure.py[DEBUG]: Skipping module named apt_configure, no package 'mirror' located

If I then add a “mirror” section to the cloud config I get:

apt_mirror: http://us.archive.ubuntu.com/ubuntu

The error is:

Dec 21 00:41:59 ubuntu1404x64 [CLOUDINIT] util.py[DEBUG]: Running apt_configure (<module 'cloudinit.config.cc_apt_configure' from '/usr/lib/python2.7/dist-packages/cloudinit/config/cc_apt_configure.pyc'>) failed#012Traceback (most recent call last):#012  File "/usr/lib/python2.7/dist-packages/cloudinit/stages.py", line 658, in _run_modules#012    cc.run(run_name, mod.handle, func_args, freq=freq)#012  File "/usr/lib/python2.7/dist-packages/cloudinit/cloud.py", line 63, in run#012    return self._runners.run(name, functor, args, freq, clear_on_fail)#012  File "/usr/lib/python2.7/dist-packages/cloudinit/helpers.py", line 197, in run#012    results = functor(*args)#012  File "/usr/lib/python2.7/dist-packages/cloudinit/config/cc_apt_configure.py", line 55, in handle#012    mirrors = find_apt_mirror_info(cloud, cfg)#012  File "/usr/lib/python2.7/dist-packages/cloudinit/config/cc_apt_configure.py", line 265, in find_apt_mirror_info#012    mirror_info.update({'primary': mirror})#012AttributeError: 'str' object has no attribute 'update'

Any ideas?