SASLHandler fails on binary data for mechanism GSSAPI
Reported by thpo:
bug description
When using gajim with Kerberos authorization, it fails to utf8-decode and print the data received, because it is binary.
bug analysis
The SASLHandler in nbxmpp/auth_nb.py assumes the data transmitted by the SASL mechanism is somehow printable.
fix recommendation
Do not utf8-decode or print the data transmitted for GSSAPI.