Grasshopper Python default encoding - how to set UTF-8?

Hello
I’m trying to save cyrillic UTF-8 string to shapefile with python plugin “pyshp”.

Error is

Runtime error (EncoderFallbackException): 'ascii' codec can't decode byte 0 in position 0: ordinal not in range
Traceback:
  line 891, in _Writer__dbfRecords, "C:\Program Files\Rhinoceros 5 (64-bit)\Plug-ins\IronPython\Lib\shapefile.py"
  line 1005, in saveDbf, "C:\Program Files\Rhinoceros 5 (64-bit)\Plug-ins\IronPython\Lib\shapefile.py"
  line 1033, in save, "C:\Program Files\Rhinoceros 5 (64-bit)\Plug-ins\IronPython\Lib\shapefile.py"

In Python 2.7 when “coding: UTF-8” was set everything works fine.
So, how to set default encoding in IronPython for Grasshopper?

What is the python plugin “pyshp”?