422 error running gh-issues-import.py

gistfile1.sh-session

Traceback (most recent call last):
  File "gh-issues-import.py", line 207, in send_request
    response = urllib.request.urlopen(req)
  File "/usr/local/Cellar/python3/3.4.1/Frameworks/Python.framework/Versions/3.4/lib/python3.4/urllib/request.py", line 153, in urlopen
    return opener.open(url, data, timeout)
  File "/usr/local/Cellar/python3/3.4.1/Frameworks/Python.framework/Versions/3.4/lib/python3.4/urllib/request.py", line 461, in open
    response = meth(req, response)
  File "/usr/local/Cellar/python3/3.4.1/Frameworks/Python.framework/Versions/3.4/lib/python3.4/urllib/request.py", line 571, in http_response
    'http', request, response, code, msg, hdrs)
  File "/usr/local/Cellar/python3/3.4.1/Frameworks/Python.framework/Versions/3.4/lib/python3.4/urllib/request.py", line 499, in error
    return self._call_chain(*args)
  File "/usr/local/Cellar/python3/3.4.1/Frameworks/Python.framework/Versions/3.4/lib/python3.4/urllib/request.py", line 433, in _call_chain
    result = func(*args)
  File "/usr/local/Cellar/python3/3.4.1/Frameworks/Python.framework/Versions/3.4/lib/python3.4/urllib/request.py", line 579, in http_error_default
    raise HTTPError(req.full_url, code, msg, hdrs, fp)
urllib.error.HTTPError: HTTP Error 422: Unprocessable Entity

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "gh-issues-import.py", line 445, in <module>
    import_issues(issues)
  File "gh-issues-import.py", line 390, in import_issues
    result_label = import_label(label)
  File "gh-issues-import.py", line 277, in import_label
    result_label = send_request('target', "labels", source)
  File "gh-issues-import.py", line 219, in send_request
    error_message += "\nDETAILS: " + error_details['message'] + "\nERRORS: " + "\n".join(error_details['errors'])
TypeError: sequence item 0: expected str instance, dict found