bug#35739: Bad signature from GNU ELPA

[Richard Copley]

Recipe from 'emacs -Q': [M-x package-list-packages RET].

Symptoms: The package list is displayed but an *Error* buffer pops up:

Failed to verify signature archive-contents.sig:
Bad signature from 474F05837FBDEF9B GNU ELPA Signing Agent (2014) <elpasign@elpa.gnu.org>
Command output:
gpg: Signature made 05/14/19 22:10:03 GMT Summer Time
gpg:                using DSA key CA442C00F91774F17F59D9B0474F05837FBDEF9B
gpg: BAD signature from "GNU ELPA Signing Agent (2014) <elpasign@elpa.gnu.org>" [unknown]

GPG version:

gpg (GnuPG) 2.2.11
libgcrypt 1.8.4
Copyright (C) 2018 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Home: C:/Users/buster/AppData/Roaming/gnupg
Supported algorithms:
Pubkey: RSA, ELG, DSA, ECDH, ECDSA, EDDSA
Cipher: IDEA, 3DES, CAST5, BLOWFISH, AES, AES192, AES256, TWOFISH,
        CAMELLIA128, CAMELLIA192, CAMELLIA256
Hash: SHA1, RIPEMD160, SHA256, SHA384, SHA512, SHA224
Compression: Uncompressed, ZIP, ZLIB, BZIP2

In GNU Emacs 27.0.50 (build 7, x86_64-w64-mingw32)
 of 2019-05-12 built on MACHINE
Repository revision: 9e1bb6a2f6c2462b9652ffce706c549269740307
Repository branch: buster
Windowing system distributor 'Microsoft Corp.', version 10.0.18890
System Description: Microsoft Windows 10 Pro (v10.0.1903.18890.1000)

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
Importing package-keyring.gpg...done
Package refresh done
error in process filter: package--check-signature-content: Failed to verify signature: "archive-contents.sig"
error in process filter: Failed to verify signature: "archive-contents.sig"

Configured using:
 'configure --config-cache --with-modules --without-pop --without-dbus
 --without-gconf --without-gsettings CFLAGS=-O3'

Configured features:
XPM JPEG TIFF GIF PNG RSVG SOUND NOTIFY W32NOTIFY ACL GNUTLS LIBXML2
ZLIB TOOLKIT_SCROLL_BARS MODULES THREADS JSON PDUMPER LCMS2 GMP

Important settings:
  value of $EMACSLOADPATH: c:\emacs-lisp;
  value of $LANG: ENG
  locale-coding-system: cp1252

Major mode: Package Menu

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  buffer-read-only: t
  line-number-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug sendmail help-mode mm-archive message
dired dired-loaddefs format-spec rfc822 mml mml-sec epa derived
gnus-util rmail rmail-loaddefs text-property-search time-date mailabbrev
gmm-utils mailheader mm-decode mm-bodies mm-encode mail-utils gnutls
network-stream url-http mail-parse rfc2231 rfc2047 rfc2045 mm-util
ietf-drums mail-prsvr url-gw nsm rmc puny url-cache url-auth url
url-proxy url-privacy url-expand url-methods url-history url-cookie
url-domsuf url-util mailcap epg finder-inf package easymenu epg-config
url-handlers url-parse auth-source cl-seq eieio eieio-core cl-macs
eieio-loaddefs password-cache json subr-x map url-vars seq byte-opt gv
bytecomp byte-compile cconv cl-loaddefs cl-lib elec-pair mule-util
tooltip eldoc electric uniquify ediff-hook vc-hooks lisp-float-type
mwheel dos-w32 ls-lisp disp-table term/w32-win w32-win w32-vars
term/common-win tool-bar dnd fontset image regexp-opt fringe
tabulated-list replace newcomment text-mode elisp-mode lisp-mode
prog-mode register page menu-bar rfn-eshadow isearch timer select
scroll-bar mouse jit-lock font-lock syntax facemenu font-core
term/tty-colors frame cl-generic cham georgian utf-8-lang misc-lang
vietnamese tibetan thai tai-viet lao korean japanese eucjp-ms cp51932
hebrew greek romanian slovak czech european ethiopic indian cyrillic
chinese composite charscript charprop case-table epa-hook jka-cmpr-hook
help simple abbrev obarray minibuffer cl-preloaded nadvice loaddefs
button faces cus-face macroexp files text-properties overlay sha1 md5
base64 format env code-pages mule custom widget hashtable-print-readable
backquote threads w32notify w32 lcms2 multi-tty make-network-process
emacs)

Memory information:
((conses 16 76305 10007)
 (symbols 48 8292 1)
 (strings 32 24152 2632)
 (string-bytes 1 719178)
 (vectors 16 12539)
 (vector-slots 8 154153 12968)
 (floats 8 25 327)
 (intervals 56 2362 126)
 (buffers 992 13))