"It's just a joke command, and not useful at all." with the last release 8 years ago. I understand that Meta didn't mind conflicting with that.
Doesn't matter. If anyone used a name at any point in time before you can never use it again. Apparently.
I would be more concerned about the ease of mistyping `ls` as `sl`, especially if you tried to list a directory whose name is a destructive Sapling command.
I'm sure Meta will rename their project to accommodate the choo-choo train