bug#22440: 25.1.50; package.el fails to install with package-check-signature t

[Mark Oteiza]

>From -Q:

(package-initialize)
(setq package-check-signature t)
M-x package-import-keyring RET /path/to/package-keyring.gpg RET
M-x list-packages RET

Attempt to install a package; in this case, debbugs:

  Unsigned file ‘async-1.6.tar’ at http://elpa.gnu.org/packages/

In GNU Emacs 25.1.50.1 (x86_64-unknown-linux-gnu, X toolkit, cairo version 
1.14.6, Xaw scroll bars)
 of 2016-01-22 built on logos
Repository revision: 9b2375008348da99b5ec414cd3ca8c4669a12576
Configured using:
 'configure --prefix=/usr --sysconfdir=/etc --libexecdir=/usr/lib
 --localstatedir=/var --without-gconf --without-imagemagick --with-cairo
 --with-modules --with-x-toolkit=lucid 'CFLAGS=-march=x86-64
 -mtune=generic -O0 -pipe -fstack-protector-strong
 --param=ssp-buffer-size=4 -g -fvar-tracking-assignments -g
 -fvar-tracking-assignments'
 LDFLAGS=-Wl,-O0,--sort-common,--as-needed,-z,relro'

Configured features:
XPM JPEG TIFF GIF PNG RSVG CAIRO SOUND GPM DBUS GSETTINGS NOTIFY ACL
GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB TOOLKIT_SCROLL_BARS
LUCID X11 MODULES

Important settings:
  value of $LC_COLLATE: C
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix