Apparently since the release of bash v. 5 some weeks ago (witnessed on Arch Linux and Debian Buster), the default behaviour of invoking the editor in vi mode has changed.
set -o vi <Esc>v
bash 4.x and earlier: an empty
$EDITOR pops up.
$EDITOR opens with the last executed command (resembling the
Accidental opening of the command-line editor and violently
:q!ing it leads to the repeated execution of the last command.
For a long-time vi-mode addict, this is unexpected behaviour and violates the principle of least astonishment.
How to revert to the old empty-editor state?