bug activity entries list is empty

[Markus Zoeller (markus_z)]

The list of activity entries for a bug is empty.

For example https://bugs.launchpad.net/nova/+bug/1533876:

    api-link:
    https://api.launchpad.net/1.0/bugs/1533876/activity

shows:

    {
 "total_size": 34,
 "start": 0,
 "entries": [],
 "resource_type_link": "https://api.launchpad.net/1.0/#bug_activity-page-resource"
    }

The 34 activities cannot be queried. The following code should print
34 lines of activities:

    import os
    from launchpadlib.launchpad import Launchpad

    cachedir = os.path.expanduser("~/.launchpadlib/cache/")
    if not os.path.exists(cachedir):
        os.makedirs(cachedir, 0700)
    launchpad = Launchpad.login_anonymously('just testing',
                                            'production', cachedir)

    bug = launchpad.bugs[1533876]

    for a in bug.activity:
        print(a.whatchanged)