github2youtrack XML parsing error

I try to import GitHub Issues to YouTrack as described here: https://www.jetbrains.com/help/youtrack/incloud/import-from-github.html,

but get a Python error:

```root@1fee2b9a94cb:/usr/src/app# github2youtrack -t perm:__YOUTRACK_TOKEN__ https://iqb.myjetbrains.com _GH_USER_ _GH_password_ iqb-berlin/testcenter-iqb-php
Traceback (most recent call last):
File "/usr/local/bin/github2youtrack", line 8, in <module>
sys.exit(main())
File "/usr/local/lib/python2.7/site-packages/youtrackutils/github2youtrack.py", line 131, in main
csv2youtrack.csv2youtrack(params)
File "/usr/local/lib/python2.7/site-packages/youtrackutils/csv2youtrack.py", line 245, in csv2youtrack
importer.import_csv()
File "/usr/local/lib/python2.7/site-packages/youtrackutils/csv2youtrack.py", line 275, in import_csv
self.do_import(projects, new_projects_owner_login)
File "/usr/local/lib/python2.7/site-packages/youtrack/youtrackImporter.py", line 25, in do_import
self._create_custom_fields(project_ids)
File "/usr/local/lib/python2.7/site-packages/youtrack/youtrackImporter.py", line 48, in _create_custom_fields
self._create_field(yt_field[NAME], yt_field[TYPE], yt_field.get(POLICY), yt_field[AUTO_ATTACHED])
File "/usr/local/lib/python2.7/site-packages/youtrack/youtrackImporter.py", line 42, in _create_field
create_custom_field(self._target, field_type, field_name, auto_attached, bundle_policy=attach_bundle_policy)
File "/usr/local/lib/python2.7/site-packages/youtrack/importHelper.py", line 50, in create_custom_field
field = _get_custom_field(connection, cf_name)
File "/usr/local/lib/python2.7/site-packages/youtrack/importHelper.py", line 22, in _get_custom_field
existing_fields = [item for item in connection.getCustomFields() if utf8encode(item.name).lower() ==
File "/usr/local/lib/python2.7/site-packages/youtrack/connection.py", line 855, in getCustomFields
xml = minidom.parseString(content)
File "/usr/local/lib/python2.7/xml/dom/minidom.py", line 1928, in parseString
return expatbuilder.parseString(string)
File "/usr/local/lib/python2.7/xml/dom/expatbuilder.py", line 940, in parseString
return builder.parseString(string)
File "/usr/local/lib/python2.7/xml/dom/expatbuilder.py", line 223, in parseString
parser.Parse(string, True)
xml.parsers.expat.ExpatError: syntax error: line 1, column 0

```

I also tried with YT-username and password but get the very same error.

I have a root-user in YT.

Any suggestions?

My Python-Environment (Dockerfile):

```

FROM python:2

WORKDIR /usr/src/app

RUN pip install youtrack-scripts

CMD tail -f /dev/null

```