/usr/share/live/build/hooks/normal/0150-remove-mdadm-configuration.hook.chroot is in open-infrastructure-system-build 20161101-lts2-2.
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 | #!/bin/sh
set -e
# Remove generated files
rm -f /etc/mdadm/mdadm.conf
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