More canonical test.
There is an exception happening around here in some cases when connection is dropped while waiting for answer. Not sure that this fixes it but this is anyhow better.
#!/bin/sh
LC_ALL=ru_RU.utf-8
export DISPLAY=:42
Xvfb $DISPLAY -screen 0 1280x1024x24 &
sleep 1
ret=0
DELAY=400
KILL_DELAY=$(($DELAY + 30))
timeout -k $KILL_DELAY $DELAY pytest --timeout=10 ./tests/tools
ret=$?
pkill -9 Xvfb
exit $ret