/usr/share/bash-completion/completions/manila.bash_completion is in python-manilaclient-doc 1.11.0-2.
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  | _manila()
{
    local cur prev opts
    COMPREPLY=()
    cur="${COMP_WORDS[COMP_CWORD]}"
    prev="${COMP_WORDS[COMP_CWORD-1]}"
    opts="$(manila bash_completion)"
    COMPLETION_CACHE=~/.manilaclient/*/*-cache
    opts+=" "$(cat $COMPLETION_CACHE 2> /dev/null | tr '\n' ' ')
    COMPREPLY=( $(compgen -W "${opts}" -- ${cur}) )
}
complete -F _manila manila
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