/etc/pm/sleep.d/10_unattended-upgrades-hibernate is in unattended-upgrades 0.83.3.2+deb8u1.
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 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 | #!/bin/sh
# Action script ensure that unattended-upgrades is finished 
# before a hibernate 
#
# Copyright: Copyright (c) 2009 Michael Vogt
# License:   GPL-2
#
PATH=/sbin:/usr/sbin:/bin:/usr/bin
SHUTDOWN_HELPER=/usr/share/unattended-upgrades/unattended-upgrade-shutdown
if [ -x /usr/bin/python3 ]; then
    PYTHON=python3
else
    PYTHON=python
fi
if [ ! -x /usr/share/unattended-upgrades/unattended-upgrade-shutdown ]; then
	exit 0
fi
case "${1}" in
        hibernate)
                if [ -e $SHUTDOWN_HELPER ]; then
         	    $PYTHON $SHUTDOWN_HELPER
                fi
                ;;
        resume|thaw)
		# nothing
                ;;
esac
 |