bug#22135: 24.3; "hangul is undefined" in minibuffer terminates isearch

[dto xelf.me]

When doing the C-s interactive search and typing the search text in the
minibuffer, pressing spacebar causes the isearch input to terminate with
the message "<Hangul> is undefined" and I have to restart the
search. The search term when restarting, now includes the space and i
can continue searching for things with spaces in them, however having to
restart the isearch every time has become a nightmare. But this suggests
that the space is being entered into the search text successfully,
before the Hangul error. (See the Recent Input below for it showing SPC
then <Hangul>.) I don't have a hangul key as this is a standard USA
keyboard.

I got a new Logitech USB wireless keyboard and updated my distro's
packages on the same day, and then this started showing up. So i'm not
sure if it's the keyboard or the upgrade.

M-x report-emacs-bug info follows:

In GNU Emacs 24.3.1 (x86_64-pc-linux-gnu, GTK+ Version 3.10.7)
 of 2014-03-07 on lamiak, modified by Debian
Windowing system distributor `The X.Org Foundation', version 11.0.11501000
System Description:     Linux Mint 17.2 Rafaela

Configured using:
 `configure '--build' 'x86_64-linux-gnu' '--build' 'x86_64-linux-gnu'
 '--prefix=/usr' '--sharedstatedir=/var/lib' '--libexecdir=/usr/lib'
 '--localstatedir=/var/lib' '--infodir=/usr/share/info'
 '--mandir=/usr/share/man' '--with-pop=yes'

'--enable-locallisppath=/etc/emacs24:/etc/emacs:/usr/local/share/emacs/24.3/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/24.3/site-lisp:/usr/share/emacs/site-lisp'
 '--with-crt-dir=/usr/lib/x86_64-linux-gnu' '--with-x=yes'
 '--with-x-toolkit=gtk3' '--with-toolkit-scroll-bars'
 'build_alias=x86_64-linux-gnu' 'CFLAGS=-g -O2 -fstack-protector
 --param=ssp-buffer-size=4 -Wformat -Werror=format-security -Wall'
 'LDFLAGS=-Wl,-Bsymbolic-functions -Wl,-z,relro'
 'CPPFLAGS=-D_FORTIFY_SOURCE=2''

Important settings:
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix
  default enable-multibyte-characters: t

Major mode: Help

Minor modes in effect:
  shell-dirtrack-mode: t
  erc-track-mode: t
  erc-track-minor-mode: t
  erc-services-mode: t
  erc-ring-mode: t
  erc-notify-mode: t
  erc-networks-mode: t
  erc-netsplit-mode: t
  erc-menu-mode: t
  erc-match-mode: t
  erc-log-mode: t
  erc-pcomplete-mode: t
  erc-button-mode: t
  erc-fill-mode: t
  erc-stamp-mode: t
  erc-autojoin-mode: t
  recentf-mode: t
  erc-smiley-mode: t
  erc-irccontrols-mode: t
  erc-noncommands-mode: t
  erc-readonly-mode: t
  erc-scrolltobottom-mode: t
  winner-mode: t
  iswitchb-mode: t
  display-time-mode: t
  show-paren-mode: t
  desktop-save-mode: t
  diff-auto-refine-mode: t
  icomplete-mode: t
  tooltip-mode: t
  mouse-wheel-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

Recent input:
<right> <right> <right> <right> <right> <right> <right> 
<right> <right> <right> <right> <right> <right> <right> 
<right> <right> <right> <right> <right> <right> <right> 
<right> <right> <right> <right> <right> " <left> <left> 
<left> <left> <left> <left> <left> <left> <left> <left> 
<left> <left> <left> <left> <left> <left> <left> <left> 
<left> <left> <left> <left> <left> <left> " C-e SPC 
<Hangul> e r r o r SPC i n SPC m i n i b u f f e r 
<down> <down> <C-tab> <f6> <f7> <C-tab> C-s C-s SPC 
SPC <backspace> <backspace> <backspace> SPC C-g C-g 
<C-tab> C-x b . l i s <return> C-s h a n g u l C-s 
C-g C-g C-s d e f c l a s s SPC <Hangul> M-x w <backspace> 
s e t - v a r i a b l e <return> * d <backspace> <backspace> 
d e b u g - o n - e r r o r <return> t <return> M-< 
C-s d e f c l a s s SPC <Hangul> <C-tab> <C-tab> M-x 
v i e w - l o s s a g e <return> <up> <up> <up> <up> 
<down> <down> <up> <up> <up> <left> <left> <left> <left> 
<left> <left> <left> <left> <left> <left> <left> <left> 
<left> <left> <left> <left> <left> <left> <down> <left> 
<right> <right> <right> <right> <right> <right> <right> 
<right> <right> <right> <right> <right> <right> <right> 
<right> <right> <right> <right> <right> <right> <right> 
<right> <right> <left> <left> <left> <left> <left> 
<left> <left> <left> <left> <right> <right> <right> 
<right> <right> <right> <right> <right> <right> <right> 
<right> <right> <left> C-SPC <C-left> <C-left> C-w 
<escape> <escape> <escape> <left> <left> <left> <left> 
C-SPC <down> <down> <down> <down> <right> <up> <down> 
<right> <right> <right> <right> <right> <right> <right> 
<right> <right> <right> C-g C-g C-x C-g M-x <up> <down> 
<up> <up> <down> <up> <up> <return>

Recent messages:
Mark set
Mark saved where search started
Type "q" to restore previous buffer.
You can run the command `view-lossage' with C-h l
Type "q" to restore previous buffer.
Desktop saved in ~/.emacs.d/
Auto-saving...done
Mark set
byte-code: Buffer is read-only: #<buffer *Help*>
Mark set
Quit [2 times]

Load-path shadows:
/usr/share/emacs24/site-lisp/cmake-data/cmake-mode hides
/usr/share/emacs/site-lisp/cmake-mode
/usr/share/emacs/24.3/site-lisp/debian-startup hides
/usr/share/emacs/site-lisp/debian-startup

Features:
(cus-edit cus-start cus-load shadow sort mail-extr emacsbug sendmail
debug help-mode view misearch multi-isearch dabbrev pcmpl-unix shell
smiley gnus-art mm-uu mml2015 epg-config mm-view mml-smime smime dig
mailcap gnus-sum nnoo gnus-group gnus-undo nnmail mail-source gnus-start
gnus-spec gnus-int gnus-range message rfc822 mml mml-sec mm-decode
mm-bodies mm-encode mail-parse rfc2231 rfc2047 rfc2045 ietf-drums
mailabbrev gmm-utils mailheader gnus-win gnus gnus-ems nnheader
mail-utils network-stream starttls tls erc-track erc-services erc-ring
erc-notify erc-networks erc-netsplit erc-menu erc-match erc-log
erc-pcomplete erc-button erc-fill erc-stamp erc-join xiomacs-theme
sh-script smie executable conf-mode vc-git imenu org-wl org-w3m org-vm
org-rmail org-mhe org-mew org-irc org-jsinfo org-infojs org-html org-exp
ob-exp org-exp-blocks org-agenda org-info org-gnus org-docview
org-bibtex bibtex org-bbdb screenwriter init org-mouse org ob-tangle
ob-ref ob-lob ob-table org-footnote org-src ob-comint ob-keys
org-pcomplete pcomplete org-list org-faces org-entities org-version
ob-emacs-lisp ob org-compat org-macs ob-eval org-loaddefs find-func
cal-menu calendar cal-loaddefs recentf tree-widget wid-edit erc-goodies
erc erc-backend erc-compat format-spec auth-source eieio gnus-util
mm-util mail-prsvr password-cache dired-x dired winner iswitchb time
slime-indentation slime-cl-indent cl-indent slime-sprof slime-asdf grep
warnings slime-fancy slime-trace-dialog slime-fontifying-fu
slime-package-fu slime-references slime-compiler-notes-tree
slime-scratch slime-presentations advice advice-preload bridge
slime-fuzzy slime-fancy-trace slime-fancy-inspector slime-c-p-c
slime-editing-commands slime-autodoc eldoc slime-repl slime-parse slime
byte-opt bytecomp byte-compile cconv derived help-fns gud apropos
compile etags arc-mode archive-mode noutline outline pp comint
ansi-color hyperspec thingatpt browse-url slime-autoloads paren
org-install desktop magit-bisect magit-key-mode magit diff-mode log-edit
easymenu easy-mmode ring pcvs-util add-log icomplete xelf cl-macs gv cl
cl-lib rx edmacro kmacro 50magit time-date tooltip ediff-hook vc-hooks
lisp-float-type mwheel x-win x-dnd tool-bar dnd fontset image regexp-opt
fringe tabulated-list newcomment lisp-mode register page menu-bar
rfn-eshadow timer select scroll-bar mouse jit-lock font-lock syntax
facemenu font-core frame cham georgian utf-8-lang misc-lang vietnamese
tibetan thai tai-viet lao korean japanese hebrew greek romanian slovak
czech european ethiopic indian cyrillic chinese case-table epa-hook
jka-cmpr-hook help simple abbrev minibuffer loaddefs button faces
cus-face macroexp files text-properties overlay sha1 md5 base64 format
env code-pages mule custom widget hashtable-print-readable backquote
make-network-process dbusbind dynamic-setting system-font-setting
font-render-setting move-toolbar gtk x-toolkit x multi-tty emacs)