post_zone_entry Umlaute Invalid UTF-8 start byte 0xfc

[marioland]

I am running into Bad Request when posting a new USP zone entry with a Umlaut in the comment.

z1 = Zone_Entry(None, "test ", "10.2.7.0", None, "255.255.255.0", 272)
st_helper.post_zone_entry(zone_id, z1)
1261
z1 = Zone_Entry(None, "test äöü", "10.2.8.0", None, "255.255.255.0", 272)
st_helper.post_zone_entry(zone_id, z1)

pytos.common.exceptions.REST_Bad_Request_Error: 
Status code: 400
Status: 'Bad Request'
Expected status code: 201
Message: 'None'

On server side it results in
Caused by: com.ctc.wstx.exc.WstxIOException: Invalid UTF-8 start byte 0xfc (at char #29, byte #-1)

This happens with pytos 1.2.8 and TOS 20.1 HF1 build 178277.
It does not happen with ps_lib 5.9.1.

Is there a workaround for that?