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

[Bob Rogers]

   From: Eli Zaretskii <eliz@gnu.org>
   Date: Thu, 26 Jan 2023 10:12:49 +0200

   > From: Bob Rogers <rogers@rgrjr.com>
   > Date: Wed, 25 Jan 2023 23:33:42 -0800
   > Cc: 61069@debbugs.gnu.org

   > 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"?

Exactly.

   > 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.

As you like.  Should this be a comint thing, or a shell thing?

                                        -- Bob