from forum.arduino.cc
Arduino dev have solved this. Details here
If you have this problem, until an updated package is released, here is what you need to do.
- Using SSH or YunSerialTerminal, connect to the linux side of the yun.
- Edit file /usr/bin/run-bridge, changing "python bridge.py" with "python -u bridge.py" (ie: add a "-u" to the command line)
- Edit file /usr/bin/kill-bridge, again changing "python bridge.py" with "python -u bridge.py" (ie: add a "-u" to the command line)
- Type kill-bridge and re-run your sketch
