Code review comment for lp://qastaging/~astara-drivers/charms/trusty/glance/api-ready-rebase

Hi Adam

I'm seeing:

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Failed 1 tests - output below:
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unit_tests.test_glance_relations.GlanceRelationTests.test_keystone_changed_with_object_store_relation
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Captured traceback:
~~~~~~~~~~~~~~~~~~~
    Traceback (most recent call last):
      File "/home/jamespage/src/charms/landing/glance/.tox/py27/local/lib/python2.7/site-packages/mock/mock.py", line 1305, in patched
        return func(*args, **keywargs)
      File "/home/jamespage/src/charms/landing/glance/unit_tests/test_glance_relations.py", line 538, in test_keystone_changed_with_object_store_relation
        relations.keystone_changed()
      File "/home/jamespage/src/charms/landing/glance/hooks/charmhelpers/core/host.py", line 435, in wrapped_f
        f(*args, **kwargs)
      File "/home/jamespage/src/charms/landing/glance/hooks/glance_relations.py", line 347, in keystone_changed
        image_service_joined(rid)
      File "/home/jamespage/src/charms/landing/glance/hooks/glance_relations.py", line 227, in image_service_joined
        "{}:9292".format(canonical_url(CONFIGS, INTERNAL))
      File "/home/jamespage/src/charms/landing/glance/hooks/charmhelpers/contrib/openstack/ip.py", line 64, in canonical_url
        address = resolve_address(endpoint_type)
      File "/home/jamespage/src/charms/landing/glance/hooks/charmhelpers/contrib/openstack/ip.py", line 117, in resolve_address
        resolved_address = _get_address_override(endpoint_type)
      File "/home/jamespage/src/charms/landing/glance/hooks/charmhelpers/contrib/openstack/ip.py", line 99, in _get_address_override
        addr_override = config(override_key)
      File "/home/jamespage/src/charms/landing/glance/charmhelpers/core/hookenv.py", line 74, in wrapper
        res = func(*args, **kwargs)
      File "/home/jamespage/src/charms/landing/glance/charmhelpers/core/hookenv.py", line 340, in config
        subprocess.check_output(config_cmd_line).decode('UTF-8'))
      File "/usr/lib/python2.7/subprocess.py", line 566, in check_output
        process = Popen(stdout=PIPE, *popenargs, **kwargs)
      File "/usr/lib/python2.7/subprocess.py", line 710, in __init__
        errread, errwrite)
      File "/usr/lib/python2.7/subprocess.py", line 1335, in _execute_child
        raise child_exception
    OSError: [Errno 2] No such file or directory

Looks like canonical_url will need mocking out as well for this test.