/usr/lib/util-vserver/defaults/debootstrap.uri is in util-vserver 0.30.216-pre3120-1.4+b1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 | http://ftp.debian.org/debian/pool/main/d/debootstrap/debootstrap_1.0.59_all.deb
|