Quick and dirty workaround:
-download: https://github.com/E...n/httpserver.py
-ftp this file to /usr/lib/enigma2/python/Plugins/Extensions/OpenWebif/httpserver.py (overwrite the existing file)
-remove /usr/lib/enigma2/python/Plugins/Extensions/OpenWebif/httpserver.pyo
-restart Enigma2
Many thanks, this helps!