'UnicodeDecodeError' when using the API to get published sources of a PPA

I'm using the API via launchpadlib and running the following code raises an OOPS, see attachment for further details:

In [1]: thekorn = launchpad.people["thekorn"]
In [2]: thekorn.archive.getPublishedSources()
HTTPError: HTTP Error 500: Internal Server Error
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Response: {'connection': 'close',
 'content-length': '18',
 'content-type': 'text/plain',
 'date': 'Wed, 01 Apr 2009 16:58:10 GMT',
 'server': 'zope.server.http (HTTP)',
 'status': '500',
 'via': '1.1 wildcard.edge.launchpad.net',
 'x-lazr-oopsid': 'OOPS-1187ED1378',
 'x-powered-by': 'Zope (www.zope.org), Python (www.python.org)'}
Content: 'UnicodeDecodeError'
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