[Satellite6] Running satellite-backup ends in "/usr/share/katello/backup.rb:313:in `split': invalid byte sequence in US-ASCII (ArgumentError)"

Issue

Running satellite backup ends on ascii error

#satellite-backup /backup --online-backup
DEPRECATION WARNING: satellite-backup and katello-backup will be removed in Satellite 6.4, where they will be replaced by foreman-maintain
Starting backup: 2019-02-19 12:10:19 +0100
Creating backup folder /backup/satellite-backup-20190219121019
Generating metadata ... 
/usr/share/katello/backup.rb:313:in `split': invalid byte sequence in US-ASCII (ArgumentError)
    from /usr/share/katello/backup.rb:313:in `block in plugin_list'
    from /usr/share/katello/backup.rb:312:in `each'
    from /usr/share/katello/backup.rb:312:in `plugin_list'
    from /usr/share/katello/backup.rb:323:in `generate_metadata'
    from /usr/share/katello/backup.rb:440:in `block in run'
    from /usr/share/katello/backup.rb:439:in `chdir'
    from /usr/share/katello/backup.rb:439:in `run'
    from /usr/sbin/satellite-backup:18:in `<main>'