!TIL: The need of full paths to other files in a #python script which is started as cronjob is also given when another script/program is 'call'ed by that script from a path that is stated in $PATH for the user whose crontab is running the script. So if you want to start a program from /usr/sbin from a script that is started by root's crontab, it must be called with /usr/sbin/$program. $PATH seems not to apply.