/usr/lib/python2.7/dist-packages/charmtools/templates/chef/files/hooks/relation-name-relation-departed is in charm-tools 2.1.2-0ubuntu4.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
1 2 3 4 | #!/bin/bash
set -e
source $(dirname $0)/stub
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