bug#21177: 25.0.50; full width glyph breaks display in terminal

[Mark Oteiza]

Hello,

I have found a couple recipes that put display out of whack in
terminals. So far I have tried xterm, gnome-terminal, as well as screen
and tmux in each. From emacs -nw -Q:

1. M-x load-theme RET somebuiltintheme RET
2. Paste some full width glyph, e.g. 数 ツ
3. Put point on the glyph
4. C-u C-x =

Point moves after the glyph, the buffer seems to narrow, sometimes the
modeline gets doubled.

Another similar thing seems to be:

1. M-x load-theme RET somebuiltintheme RET
2. C-x 8 RET HIRAGANA TAB … (complete to something) RET

Here's the result after this second recipe https://i.imgur.com/HXyfX5l.png

In GNU Emacs 25.0.50.1 (x86_64-unknown-linux-gnu, X toolkit, Xaw scroll bars)
 of 2015-08-01 on logos
Repository revision: eb0f65b4fbbea60100b53cb40a1d7138d47ad0d2
Configured using:
 `configure --prefix=/usr --sysconfdir=/etc --libexecdir=/usr/lib
 --localstatedir=/var --without-gconf --with-x-toolkit=lucid
 'CFLAGS=-march=x86-64 -mtune=generic -O2 -pipe -fstack-protector-strong
 --param=ssp-buffer-size=4' CPPFLAGS=-D_FORTIFY_SOURCE=2
 LDFLAGS=-Wl,-O1,--sort-common,--as-needed,-z,relro'

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

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