tests/warn_conflict: fix python test script
tests/warn_conflict: fix python test script

ant9000/RIOT,OTAkeys/RIOT,OTAkeys/RIOT,OlegHahm/RIOT,authmillenon/RIOT,ant9000/RIOT,OlegHahm/RIOT,authmillenon/RIOT,ant9000/RIOT,kaspar030/RIOT,jasonatran/RIOT,jasonatran/RIOT,miri64/RIOT,OlegHahm/RIOT,authmillenon/RIOT,miri64/RIOT,kYc0o/RIOT,jasonatran/RIOT,kYc0o/RIOT,ant9000/RIOT,authmillenon/RIOT,RIOT-OS/RIOT,kaspar030/RIOT,RIOT-OS/RIOT,kYc0o/RIOT,RIOT-OS/RIOT,kaspar030/RIOT,ant9000/RIOT,OTAkeys/RIOT,miri64/RIOT,kaspar030/RIOT,kYc0o/RIOT,miri64/RIOT,RIOT-OS/RIOT,OlegHahm/RIOT,miri64/RIOT,OTAkeys/RIOT,authmillenon/RIOT,kaspar030/RIOT,jasonatran/RIOT,OTAkeys/RIOT,OlegHahm/RIOT,RIOT-OS/RIOT,kYc0o/RIOT,authmillenon/RIOT,jasonatran/RIOT