python-markdown missing in the deb packacge's dependencies

Attempt to run things like "charm proof" resulted in this error:

Traceback (most recent call last):
  File "/usr/bin/charm", line 5, in <module>
    from pkg_resources import load_entry_point
  File "/usr/lib/python2.7/dist-packages/pkg_resources.py", line 2803, in <module>
    working_set.require(__requires__)
  File "/usr/lib/python2.7/dist-packages/pkg_resources.py", line 696, in require
    needed = self.resolve(parse_requirements(requirements))
  File "/usr/lib/python2.7/dist-packages/pkg_resources.py", line 594, in resolve
    raise DistributionNotFound(req)
pkg_resources.DistributionNotFound: Markdown>=2.0.1

That is easy to fix by installing python-markdown manually -- but that package should appear in the dependencies of the charmtools package.