bug#39791: 26.3; auto-save-list-file-name should not be deleted when Emacs is terminated by SIGHUP

[Ed Sabol]

If I ssh to a remote server and start Emacs and my ssh connection is severed
sometime thereafter, causing the remote emacs process to be terminated with
SIGHUP, the auto-save-list-file-name file is deleted. I find this very
undesirable. If there's an option to change this behavior, I can't find one.

The Emacs manual says this about 'auto-save-list-file-name':

    When Emacs exits normally, it deletes this file; if Emacs crashes, you
    can look in the file to find all the auto-save files that might contain
    work that was otherwise lost. The recover-session command uses this file
    to find them.

Older versions of Emacs apparently had a different definition of "when Emacs
exits normally" compared to Emacs 26.x. Emacs 21.x, for example, does not
delete the auto-save-list-file-name file when the ssh connection is severed
and a remote emacs process is killed with SIGHUP.


In GNU Emacs 26.3 (build 1, x86_64-pc-linux-gnu, X toolkit)
 of 2019-11-19 built on heabox
Windowing system distributor 'The X.Org Foundation', version 11.0.12004000
System Description:     Scientific Linux release 7.7 (Nitrogen)

Recent messages:
Counting new messages...done (11)
Saving file /Home/lhea2/sabol/Mail/RMAIL...
Wrote /Home/lhea2/sabol/Mail/RMAIL [2 times]
Computing summary lines...done
11 new messages read
Showing message 6160...done
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Computing summary lines...done
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Configured using:
 'configure --prefix=/software/usr/contrib
 --exec-prefix=/software/usr/contrib/linux-7.x --with-x-toolkit=lucid
 --with-xft=yes --with-toolkit-scroll-bars=no --with-jpeg=no --with-gif=no
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Major mode: RMAIL

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Memory information:
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