Json output does not seem to work for binary data

[ztrnovcova]

When the output of the thrift call contains binary data, the json output option does not seem to work. The call worked without it but with it, I get exception like:
UnicodeDecodeError: 'utf8' codec can't decode byte 0xaf in position 18: invalid start byte .

Without the -j option, the output looks something like:
Response(dataList=[DataWrapper(data='2132319H895YA\x00\x00\x00\x80\xb5\xb5_\x00+\x08\x18\xc0\x84\x00..., '), DataWrapper(data='...')])