/etc/bash_completion.d/neutron.bash_completion is in python-neutronclient 2.3.6-2.
This file is owned by root:root, with mode 0o644.
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  | _neutron_opts="" # lazy init
_neutron_flags="" # lazy init
_neutron_opts_exp="" # lazy init
_neutron()
{
	local cur prev nbc cflags
	COMPREPLY=()
	cur="${COMP_WORDS[COMP_CWORD]}"
	prev="${COMP_WORDS[COMP_CWORD-1]}"
	if [ "x$_neutron_opts" == "x" ] ; then
		nbc="`neutron bash-completion`"
		_neutron_opts="`echo "$nbc" | sed -e "s/--[a-z0-9_-]*//g" -e "s/\s\s*/ /g"`"
		_neutron_flags="`echo " $nbc" | sed -e "s/ [^-][^-][a-z0-9_-]*//g" -e "s/\s\s*/ /g"`"
		_neutron_opts_exp="`echo "$_neutron_opts" | sed -e "s/\s/|/g"`"
	fi
	if [[ " ${COMP_WORDS[@]} " =~ " "($_neutron_opts_exp)" " && "$prev" != "help" ]] ; then
		COMPLETION_CACHE=~/.neutronclient/*/*-cache
		cflags="$_neutron_flags "$(cat $COMPLETION_CACHE 2> /dev/null | tr '\n' ' ')
		COMPREPLY=($(compgen -W "${cflags}" -- ${cur}))
	else
		COMPREPLY=($(compgen -W "${_neutron_opts}" -- ${cur}))
	fi
	return 0
}
complete -F _neutron neutron
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