bug#61069: 30.0.50; comint-copy-old-input should include continuation lines

[Eli Zaretskii <eliz@gnu.org>]

> From: Bob Rogers <rogers@rgrjr.com>
> Date: Wed, 25 Jan 2023 23:33:42 -0800
> Cc: 61069@debbugs.gnu.org
> 
>    Or maybe I don't understand what is this "backslash" business is
>    about?  AFAICT, the "backslashes" shown for long lines of Make output
>    are those produced by the Emacs display, not by the shell, so the code
>    you want to change should already take care of that.
> 
>    What am I missing?  Could you please show an example of "long Make
>    output" where the current code doesn't DTRT, so we'd be on the same
>    page wrt the problem?
> 
>    Thanks.
> 
> Here's an example from building emacs:
> 
> 	. . .
> 	rm -f emacs && cp -f temacs emacs
> 	LC_ALL=C ./temacs -batch  -l loadup --temacs=pdump \
> 		--bin-dest /usr/local/bin/ --eln-dest /usr/local/lib64/emacs/30.0.50/
> 	Loading loadup.el (source)...
> 	Dump mode: pdump
> 	. . .

Oh, you mean the backslashes that come from the Makefile itself, like
the one after "=pdump"?

> My thought is that C-RET on the "./temacs -batch" line in a *shell*
> buffer should take both that line and the next.

That has to be an optional feature, probably off by default.