sets.extras: change non-repeating to use remove-first!.
sets.extras: change non-repeating to use remove-first!.

bjourne/factor,bpollack/factor,bpollack/factor,nicolas-p/factor,AlexIljin/factor,bpollack/factor,AlexIljin/factor,sarvex/factor-lang,AlexIljin/factor,slavapestov/factor,AlexIljin/factor,bjourne/factor,bpollack/factor,mrjbq7/factor,dch/factor,sarvex/factor-lang,AlexIljin/factor,sarvex/factor-lang,nicolas-p/factor,dch/factor,dch/factor,mrjbq7/factor,factor/factor,factor/factor,tgunr/factor,nicolas-p/factor,dch/factor,nicolas-p/factor,mrjbq7/factor,factor/factor,sarvex/factor-lang,bpollack/factor,sarvex/factor-lang,bjourne/factor,bjourne/factor,slavapestov/factor,dch/factor,tgunr/factor,nicolas-p/factor,dch/factor,bpollack/factor,tgunr/factor,slavapestov/factor,factor/factor,sarvex/factor-lang,nicolas-p/factor,factor/factor,bjourne/factor,AlexIljin/factor,bpollack/factor,bjourne/factor,slavapestov/factor,mrjbq7/factor,bjourne/factor,tgunr/factor,AlexIljin/factor,slavapestov/factor,slavapestov/factor,mrjbq7/factor,tgunr/factor,nicolas-p/factor,tgunr/factor,slavapestov/factor,sarvex/factor-lang,factor/factor,mrjbq7/factor