bug#30874: 27.0.50; Emacs crashes

[Jan Synacek]

Emacs crashes after executing the following on the current master
(commit b39ca55e294d3be3e4c6e142975256d7f8cdfe76):

emacs -Q --eval="(switch-to-buffer \"*scratch*\")" --eval="(insert-char 
#x274c)" --eval="(set-fontset-font \"fontset-default\" 'unicode \"Dejavu Sans 
Mono\")"



In GNU Emacs 27.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.22.26)
 of 2018-03-20 built on jsynacek-ntb.brq.redhat.com
Repository revision: b39ca55e294d3be3e4c6e142975256d7f8cdfe76
Windowing system distributor 'Fedora Project', version 11.0.11906000
System Description: Fedora 27 (Workstation Edition)

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
s-x is undefined
delete-backward-char: Text is read-only

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GSETTINGS NOTIFY
ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB
TOOLKIT_SCROLL_BARS GTK3 X11 THREADS LCMS2

Important settings:
  value of $LANG: en_US.UTF-8
  value of $XMODIFIERS: @im=ibus
  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
  show-paren-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message rmc puny dired dired-loaddefs
format-spec rfc822 mml mml-sec epa derived epg gnus-util rmail
rmail-loaddefs mm-decode mm-bodies mm-encode mail-parse rfc2231
mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045 ietf-drums
mm-util mail-prsvr mail-utils elec-pair finder-inf package easymenu
epg-config url-handlers url-parse auth-source cl-seq eieio eieio-core
cl-macs eieio-loaddefs password-cache json map url-vars seq byte-opt gv
bytecomp byte-compile cconv cl-loaddefs cl-lib time-date paren mule-util
tooltip eldoc electric uniquify ediff-hook vc-hooks lisp-float-type
mwheel term/x-win x-win term/common-win x-dnd 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 dbusbind inotify lcms2 dynamic-setting system-font-setting
font-render-setting move-toolbar gtk x-toolkit x multi-tty
make-network-process emacs)

Memory information:
((conses 16 105982 7168)
 (symbols 48 21563 1)
 (miscs 40 55 107)
 (strings 32 32124 1542)
 (string-bytes 1 857535)
 (vectors 16 17159)
 (vector-slots 8 524353 8330)
 (floats 8 54 63)
 (intervals 56 201 0)
 (buffers 992 11))