[Help-bash] Readline when using “<<”? Is it recent?

[Garreau\, Alexandre]

Hi,

Recently I noticed that when I typed text after “<<”, I could delete
text, go back with arrow keys, or with emacs-like keystrokes, use M-u,
M-l, etc.  Yet I think I can remember a time where when using “<<” you
couldn’t go back and any attempt to del would result in printing a
control sequence that would need to do Ctrl+C and redo everything again
with “<<” (also including its whole stdin text in the history)…

Was readline support added for this recently? or was it possible to
enable/disable and disabled until recently in Debian? or maybe some
other corner case that made me miss it until now?