cannot serialize dict

[mcepl]

matej@mitmanek: github-issues-export (master)$ ./github_issues_export.py -b -u mcepl -w something M2Crypto/M2Crypto|&tee m2crypto-issues.txt
Traceback (most recent call last):
  File "./github_issues_export.py", line 340, in <module>
    main(cfg)
  File "./github_issues_export.py", line 333, in main
    print et.tostring(out_xml, "utf-8")
  File "/usr/lib64/python2.7/xml/etree/ElementTree.py", line 1126, in tostring
    ElementTree(element).write(file, encoding, method=method)
  File "/usr/lib64/python2.7/xml/etree/ElementTree.py", line 820, in write
    serialize(write, self._root, encoding, qnames, namespaces)
  File "/usr/lib64/python2.7/xml/etree/ElementTree.py", line 939, in _serialize_xml
    _serialize_xml(write, e, encoding, qnames, None)
  File "/usr/lib64/python2.7/xml/etree/ElementTree.py", line 939, in _serialize_xml
    _serialize_xml(write, e, encoding, qnames, None)
  File "/usr/lib64/python2.7/xml/etree/ElementTree.py", line 937, in _serialize_xml
    write(_escape_cdata(text, encoding))
  File "/usr/lib64/python2.7/xml/etree/ElementTree.py", line 1075, in _escape_cdata
    _raise_serialization_error(text)
  File "/usr/lib64/python2.7/xml/etree/ElementTree.py", line 1052, in _raise_serialization_error
    "cannot serialize %r (type %s)" % (text, type(text).__name__)
TypeError: cannot serialize {u'following_url': u'https://api.github.com/users/martinpaljak/following{/other_user}', u'events_url': u'https://api.github.com/users/martinpaljak/events{/privacy}', u'organizations_url': u'https://api.github.com/users/martinpaljak/orgs', u'url': u'https://api.github.com/users/martinpaljak', u'gists_url': u'https://api.github.com/users/martinpaljak/gists{/gist_id}', u'html_url': u'https://github.com/martinpaljak', u'subscriptions_url': u'https://api.github.com/users/martinpaljak/subscriptions', u'avatar_url': u'https://avatars.githubusercontent.com/u/46006?v=3', u'repos_url': u'https://api.github.com/users/martinpaljak/repos', u'received_events_url': u'https://api.github.com/users/martinpaljak/received_events', u'gravatar_id': u'', u'starred_url': u'https://api.github.com/users/martinpaljak/starred{/owner}{/repo}', u'site_admin': False, u'login': u'martinpaljak', u'type': u'User', u'id': 46006, u'followers_url': u'https://api.github.com/users/martinpaljak/followers'} (type dict)