/usr/share/livecd-rootfs/live-build/ubuntu-cpc/hooks/001-divert-sync.chroot_early is in livecd-rootfs 2.525.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 | #!/bin/sh
set -e
dpkg-divert --quiet --add --divert /bin/sync.REAL --rename /bin/sync
cat > /bin/sync <<'EOF'
#! /bin/sh
echo "$0: diverted by livecd-rootfs" >&2
exit 0
EOF
chmod +x /bin/sync
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