Readline Completions Duplicate bottom_toolbar

I'm working on a project where I was asked to add a bottom_toolbar. We already have some custom logic using display_completions_like_readline to do different things for tab completion. I ran into an issue where the tool bar was being duplicated above the set of completions if the current text could produce multiple completions (if you put in an expected completion it would fill in the rest of the command but not duplicate the bottom_toolbar, as desired).

Cribbing from an issue that brought this up tangentially, you can see this behavior with the code below:

#!/usr/bin/env python

from prompt_toolkit.completion import WordCompleter
from prompt_toolkit.shortcuts import CompleteStyle, prompt

test_completer = WordCompleter(['completely', 'arbitrary', 'set', 'of', 'words'])

prompt_params = {'completer': test_completer,
                 'complete_style': CompleteStyle.READLINE_LIKE,
                 'bottom_toolbar': "should only appear at the bottom"}

while True:
    prompt('> ', **prompt_params)

If you start typing one of the words, tab will complete it as expected. If you hit tab to bring up the set of completions, you will see something like this (I hit tab on the second empty prompt):

> set
>
should only appear at the bottom                                                                                                                                                                                                        
completely arbitrary  set        of         words      
>
should only appear at the bottom

Run the supplied Python reproduction using WordCompleter, prompt, bottom_toolbar, and CompleteStyle.READLINE_LIKE. Start by tracing display_completions_like_readline and the completion rendering path when multiple completions are shown. Done means the bottom toolbar appears only once while the completion list is displayed, without changing the expected single-completion behavior.