Bug#462146: xterm: backspace deletes twice much of characters for each UTF-8 character

[Németh Márton <nm127@freemail.hu>]

Package: xterm
Version: 231-1
Severity: important

When xterm is switched to UTF-8 mode it is possible to enter UTF-8 characters in bash.
However, if an UTF-8 character entered, you can press the backspace two times and it will
delete the prompt also.

Steps to reproduce:
1. Start xterm: "xterm -en UTF-8"
2. If you check "VT Fonts" menu (Ctrl+right mouse button) the UTF-8 item is set
   (See the attached 01_started_with_-en_UTF-8.png)
3. Set the keymap to US keyboard: "setxkbmap en_US"
4. Enter the some characters: "jkl;'" (See the attached
    02_some_en-US_characters_entered.png)
5. Press the backspace 5 times: the characters are deleted.
6. Press the backspace 2 more times: nothing is deleted. (See
   the attached 03_the_en-US_characters_deleted.png)
7. Set the keyboard to Hungarian: "setxkbmap hu"
8. Press the same buttons as before, this time the characters: "jkléá" are shown.
   (See the attached 04_some_hu_characters_entered.png)
9. Press the backspace 5 times: the characters are deleted.
10. Press the backspace 2 more times: two extra characters are deleted from the
    prompt. (See the attached 05_the_hu_characters_AND_the_promt_deleted.png)

Expected behavior: no more characters can be deleted than was entered.

My locale settings are:
xterm: backspace deletes twice much of characters for each UTF-8 character
$ locale
LANG=hu_HU
LANGUAGE=hu_HU:hu:en_GB:en
LC_CTYPE="hu_HU"
LC_NUMERIC="hu_HU"
LC_TIME="hu_HU"
LC_COLLATE="hu_HU"
LC_MONETARY="hu_HU"
LC_MESSAGES="hu_HU"
LC_PAPER="hu_HU"
LC_NAME="hu_HU"
LC_ADDRESS="hu_HU"
LC_TELEPHONE="hu_HU"
LC_MEASUREMENT="hu_HU"
LC_IDENTIFICATION="hu_HU"
LC_ALL=

My bash version is:
ii  bash           3.1dfsg-8      The GNU Bourne Again SHell

-- System Information:
Debian Release: lenny/sid
  APT prefers testing
  APT policy: (500, 'testing')
Architecture: i386 (i686)

Kernel: Linux 2.6.23 (PREEMPT)
Locale: LANG=hu_HU, LC_CTYPE=hu_HU (charmap=ISO-8859-2)
Shell: /bin/sh linked to /bin/bash

Versions of packages xterm depends on:
ii  libc6                     2.7-5          GNU C Library: Shared libraries
ii  libfontconfig1            2.5.0-2        generic font configuration library
ii  libice6                   2:1.0.4-1      X11 Inter-Client Exchange library
ii  libncurses5               5.6+20071215-1 Shared libraries for terminal hand
ii  libsm6                    2:1.0.3-1+b1   X11 Session Management library
ii  libx11-6                  2:1.0.3-7      X11 client-side library
ii  libxaw7                   2:1.0.4-1      X11 Athena Widget library
ii  libxext6                  1:1.0.3-2      X11 miscellaneous extension librar
ii  libxft2                   2.1.12-2       FreeType-based font drawing librar
ii  libxmu6                   1:1.0.3-1      X11 miscellaneous utility library
ii  libxt6                    1:1.0.5-3      X11 toolkit intrinsics library
ii  xbitmaps                  1.0.1-2        Base X bitmaps

Versions of packages xterm recommends:
ii  xutils                      1:7.1.ds.3-1 X Window System utility programs

-- no debconf information