[Piuparts-reports] Cron <piupartsm at pejacevic> rotate_master_logs

[Cron Daemon]

'sid-nodoc/master.log' -> 'sid-nodoc/master.20180821.log'
'buster-rcmd/master.log' -> 'buster-rcmd/master.20180821.log'
'jessie2stretch/master.log' -> 'jessie2stretch/master.20180821.log'
'jessie-pu/master.log' -> 'jessie-pu/master.20180821.log'