/usr/share/live/build/hooks/0170-remove-python-py.hook.chroot is in live-build 4.0.3-1.
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 | #!/bin/sh
set -e
# Remove Python *.py files.
#
# This removes byte-compiled Python modules to save some space.
find /usr -name "*.pyc" -print0 | xargs -0r rm -f
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