I think we'd want to include these repos in our apt sources to be able to install packages from backports if we want to:
deb http://mirrors.ocf.berkeley.edu/debian/ stretch-backports main
deb-src http://mirrors.ocf.berkeley.edu/debian/ stretch-backports main
deb http://apt.ocf.berkeley.edu/ stretch-backports main
deb-src http://apt.ocf.berkeley.edu/ stretch-backports main
I think we'd want to include these repos in our apt sources to be able to install packages from backports if we want to: