im-config hangs if LC_CTYPE does not have quotes

If LC_CTYPE does not have any quotes, regex does not hit, then im-config hangs at the point below.

/usr/share/im-config/xinputrc.common
     92 IM_CONFIG_LC_CTYPE=$(locale | sed -nr 's/LC_CTYPE=\"([a-zA-Z_]*).*\"/\1/p')
     93 IM_CONFIG_SCRIPT=$(grep $IM_CONFIG_LC_CTYPE $IM_CONFIG_LC_PREFS | grep -v '^#' | awk '{print $2}')

$ cat ~/.pam_environment
LC_CTYPE=ja_JP.UTF-8
LC_PAPER=ja_JP.UTF-8
LC_MEASUREMENT=ja_JP.UTF-8
PAPERSIZE=a4

$ locale
LANG=en_US.UTF-8
LANGUAGE=en_US
LC_CTYPE=ja_JP.UTF-8
LC_NUMERIC=en_US.UTF-8
LC_TIME=en_US.UTF-8
LC_COLLATE="en_US.UTF-8"
LC_MONETARY=en_US.UTF-8
LC_MESSAGES="en_US.UTF-8"
LC_PAPER=ja_JP.UTF-8
LC_NAME=en_US.UTF-8
LC_ADDRESS=en_US.UTF-8
LC_TELEPHONE=en_US.UTF-8
LC_MEASUREMENT=ja_JP.UTF-8
LC_IDENTIFICATION=en_US.UTF-8
LC_ALL=

$ bash -x /usr/bin/im-config
+ . /usr/share/im-config/xinputrc.common
++ IM_CONFIG_VERSION=0.27-1ubuntu3
++ IM_CONFIG_DATA=/usr/share/im-config/data
++ IM_CONFIG_LC_PREFS=/usr/share/im-config/locale_prefs.conf
++ IM_CONFIG_XINPUTRC_USR=/home/nobuto/.xinputrc
++ IM_CONFIG_XINPUTRC_SYS=/etc/X11/xinit/xinputrc
++ IM_CONFIG_DEFAULT=/etc/default/im-config
++ . gettext.sh
+++ test 'X\t' = 'X\t'
+++ echo=echo
+++ test -z ''
+++ case "$0" in
++ TEXTDOMAIN=im-config
++ export TEXTDOMAIN
++ TEXTDOMAINDIR=/usr/share/locale/
++ export TEXTDOMAINDIR
++ '[' -r /etc/default/im-config ']'
++ . /etc/default/im-config
+++ IM_CONFIG_DEFAULT_MODE=auto
++ id -u
+ '[' 1000 = 0 ']'
+ IM_CONFIG_XINPUTRC=/home/nobuto/.xinputrc
++ gettext 'user configuration'
+ IM_CONFIG_XINPUTRC_TYPE='user configuration'
++ automatic_im
++ '[' -r /usr/share/im-config/locale_prefs.conf ']'
+++ locale
+++ sed -nr 's/LC_CTYPE=\"([a-zA-Z_]*).*\"/\1/p'
++ IM_CONFIG_LC_CTYPE=
+++ grep /usr/share/im-config/locale_prefs.conf
+++ awk '{print $2}'

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: im-config 0.27-1ubuntu3
ProcVersionSignature: Ubuntu 3.19.0-9.9-generic 3.19.1
Uname: Linux 3.19.0-9-generic x86_64
ApportVersion: 2.16.2-0ubuntu3
Architecture: amd64
CurrentDesktop: Unity
Date: Fri Mar 13 22:26:12 2015
EcryptfsInUse: Yes
InstallationDate: Installed on 2015-02-28 (12 days ago)
InstallationMedia: Ubuntu 15.04 "Vivid Vervet" - Alpha amd64 (20150228)
PackageArchitecture: all
SourcePackage: im-config
UpgradeStatus: No upgrade log present (probably fresh install)