Quantal Ubuntu Desktop 20120524 failed to install: ubi-language failed with exit status 1: UnicodeError in process_line() in filteredcommand.py

Quantal Ubuntu Desktop 20120524 automated test failed in ubi-language

Error from debug log:
""""
May 24 09:07:28 ubiquity: Starting up '['log-output', '-t', 'ubiquity', '--pass-stdout', '/usr/lib/ubiquity/localechooser/localechooser']' for ubi-language.Page
May 24 09:07:28 ubiquity: Watching for question patterns localechooser/languagelist
May 24 09:07:28 debconf (filter): <-- CAPB backup
May 24 09:07:28 debconf (filter): <-- REGISTER debian-installer/language debconf/language
update_release_notes_label()
May 24 09:07:28 debconf (filter): <-- SUBST localechooser/languagelist CODES C, sq, am, ar, ast, eu, be, bn, bs, bg, my, ca, zh_CN, zh_TW, hr, cs, da, nl, dz, en, eo, et, fi, fr, gl, ka, de, el, gu, he, hi, hu, is, id, ga, it, ja, kn, kk, km, ko, ku, lo, lv, lt, mk, ml, mr, ne, se_NO, nb_NO, nn_NO, fa, pl, pt, pt_BR, pa, ro, ru, sr, si, sk, sl, es, sv, tl, ta, te, th, bo, tr, uk, ug, vi
May 24 09:07:28 debconf (filter): <-- SUBST localechooser/languagelist NAMES_EN C, Albanian, Amharic, Arabic, Asturian, Basque, Belarusian, Bengali, Bosnian, Bulgarian, Burmese, Catalan, Chinese (Simplified), Chinese (Traditional), Croatian, Czech, Danish, Dutch, Dzongkha, English, Esperanto, Estonian, Finnish, French, Galician, Georgian, German, Greek, Gujarati, Hebrew, Hindi, Hungarian, Icelandic, Indonesian, Irish, Italian, Japanese, Kannada, Kazakh, Khmer, Korean, Kurdish, Lao, Latvian, Lithuanian, Macedonian, Malayalam, Marathi, Nepali, Northern Sami, Norwegian Bokmaal, Norwegian Nynorsk, Persian, Polish, Portuguese, Portuguese (Brazil), Punjabi (Gurmukhi), Romanian, Russian, Serbian (Cyrillic), Sinhala, Slovak, Slovenian, Spanish, Swedish, Tagalog, Tamil, Telugu, Thai, Tibetan, Turkish, Ukrainian, Uyghur, Vietnamese
Exception caught in process_line:
Traceback (most recent call last):
  File "/usr/lib/ubiquity/ubiquity/filteredcommand.py", line 135, in process_line
    return self.dbfilter.process_line()
  File "/usr/lib/ubiquity/ubiquity/debconffilter.py", line 258, in process_line
    self.debug('filter', '<--', command, *params)
  File "/usr/lib/ubiquity/ubiquity/debconffilter.py", line 116, in debug
    file=sys.stderr)
UnicodeEncodeError: 'ascii' codec can't encode characters in position 167-170: ordinal not in range(128)
May 24 09:07:28 ubiquity: ['log-output', '-t', 'ubiquity', '--pass-stdout', '/usr/lib/ubiquity/localechooser/localechooser'] exited with code 1
""""

ProblemType: Bug
DistroRelease: Ubuntu 12.10
Package: ubiquity 2.11.1
ProcVersionSignature: Ubuntu 3.4.0-3.7-generic 3.4.0
Uname: Linux 3.4.0-3-generic x86_64
ApportVersion: 2.1-0ubuntu1
Architecture: amd64
CasperVersion: 1.317
Date: Thu May 24 09:29:12 2012
InstallCmdLine: boot=casper DEBCONF_DEBUG=developer -- debconf/priority=critical locale=en_US console-setup/ask_detect=false console-setup/layoutcode=us keyboard-configuration/layoutcode=fr keyboard-configuration/variantcode=oss noprompt console=ttyS0 automatic-ubiquity initrd=initrd.22c675df-c08c-4a41-999f-15c8ff818e6e BOOT_IMAGE=kernel.22c675df-c08c-4a41-999f-15c8ff818e6e
LiveMediaBuild: Ubuntu 12.10 "Quantal Quetzal" - Alpha amd64 (20120524)
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)