On Arch Linux, for some reason, when I try to start nginx with the command "systemctl start nginx", it fails, with this being the output of "systemctl status nginx":

Loaded: loaded (/etc/systemd/system/nginx.service; enabled)
Active: failed (Result: exit-code) since Wed 2013-10-30 16:22:17 EDT; 5s ago
Process: 9835 ExecStop=/usr/bin/chroot --userspec=http:http /home/nginx /usr/bin/nginx -g pid /run/nginx.pid; -s quit (code=exited, status=126)
Process: 3982 ExecStart=/usr/bin/chroot --userspec=http:http /home/nginx /usr/bin/nginx -g pid /run/nginx.pid; daemon on; master_process on; (code=exited, status=0/SUCCESS)
Process: 10967 ExecStartPre=/usr/bin/chroot --userspec=http:http /home/nginx /usr/bin/nginx -t -q -g pid /run/nginx.pid; daemon on; master_process on; (code=exited, status=126)
Main PID: 3984 (code=exited, status=0/SUCCESS)
CGroup: /system.slice/nginx.service

...but when I run

/usr/bin/chroot --userspec=http:http /home/nginx /usr/bin/nginx -t -q -g "pid /run/nginx.pid; daemon on; master_process on;"

and then

/usr/bin/chroot --userspec=http:http /home/nginx /usr/bin/nginx -g "pid /run/nginx.pid; daemon on; master_process on;"

as root, all it does is return a warning, but works just fine:

nginx: [warn] the "user" directive makes sense only if the master process runs with super-user privileges, ignored in /etc/nginx/nginx.conf:1

Why is it doing that?