mongodb on vivid - install hook fails with: ImportError: No module named yaml

mongodb on vivid - install hook fails with: ImportError: No module named yaml

# On the mongodb/0 unit:
2015-04-15 20:38:58 INFO unit.mongodb/0.install logger.go:40 Traceback (most recent call last):
2015-04-15 20:38:58 INFO unit.mongodb/0.install logger.go:40 File "/var/lib/juju/agents/unit-mongodb-0/charm/hooks/install", line 16, in <module>
2015-04-15 20:38:58 INFO unit.mongodb/0.install logger.go:40 import yaml
2015-04-15 20:38:58 INFO unit.mongodb/0.install logger.go:40 ImportError: No module named yaml
2015-04-15 20:38:58 ERROR juju.worker.uniter.operation runhook.go:89 hook "install" failed: exit status 1

ubuntu@juju-beisx2-machine-9:~$ dpkg -l | grep yaml
ii libyaml-0-2:amd64 0.1.6-3 amd64 Fast YAML 1.1 parser and emitter library
ii python3-yaml 3.11-2 amd64 YAML parser and emitter for Python3

ubuntu@juju-beisx2-machine-9:~$ python
Python 2.7.9 (default, Apr 2 2015, 15:33:21)
[GCC 4.9.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import yaml
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: No module named yaml