preinst is in bash-completion 1:1.3-1ubuntu8.
This file is a maintainer script. It is executed when installing (*inst) or removing (*rm) the package.
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 | #!/bin/sh
set -e
for file in repomanage modules mock dcop bluez-utils; do
	dpkg-maintscript-helper rm_conffile /etc/bash_completion.d/$file \
		1:1.3-1ubuntu6 -- "$@"
done
case "$1" in
    install|upgrade)
	if [ -e /usr/share/doc/bash/completion-contrib ]; then
	    rm -rf /usr/share/doc/bash/completion-contrib
	fi
    ;;
    abort-upgrade)
    ;;
    *)
        echo "preinst called with unknown argument \`$1'" >&2
        exit 1
    ;;
esac
exit 0
 |