bug#59622: 29.0.50; [PATCH] Regression in Eshell's handling of escaped newlines

[Jim Porter <jporterbugs@gmail.com>]

On 11/26/2022 4:36 PM, Jim Porter wrote:
> Starting from "emacs -Q -f eshell":
> 
>    # Emacs 28
>    ~ $ echo foo\
>    bar
> 
>    foobar
> 
>    # Emacs 29
>    ~ $ echo foo\
>    bar
> 
>    foo
>    bar
> 
> That is, Emacs 28 used to treat escaped newlines in the way you'd expect 
> from other shells: it expands to the empty string. Now in Emacs 29, it 
> inserts a literal newline.

Eli, since this is a regression from Emacs 28 (likely fallout from one 
of my changes to fix some longstanding bugs with quotes in Eshell), 
would my current patch be ok on the release branch? I can try to 
minimize the changes a bit further (I slightly refactored 
'eshell-parse-backslash' to reduce repetition), but since it has unit 
tests, I think it should be pretty safe either way.