[issue37766] IDLE autocomplete: revise fetch_completions, add htest

[E. Paine]

Change by E. Paine <xepaine13 at gmail.com>:


----------
nosy: +epaine
versions: +Python 3.10, Python 3.11 -Python 3.7, Python 3.8

_______________________________________
Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue37766>
_______________________________________