I was a little confused by the subject of this bug since this has nothing to do with systemd. Neither the script nor the init call has any connection to systemd.
The issue here is that the init script (/etc/init.d/single) is trying to call SysV init with the "-t1" flag, which is not valid. There is no -t flag or -t1 flag for init. I suspect what the script was intended to do is call "/sbin/telinit -t 1 s". This would switch to single user mode after a delay of just one second. - Jesse
