apt-add-repository faces exception with UnicodeDecodeError: 'ascii' codec can't decode byte 0xe3 in position 27: ordinal not in range(128)

[Nobuto Murata]

apt-add-repository exits with exception message below

$ sudo apt-add-repository ppa:gm-dev-launchpad/ppa

Exception in thread Thread-1:
Traceback (most recent call last):
  File "/usr/lib/python2.6/threading.py", line 532, in __bootstrap_inner
    self.run()
  File "/usr/lib/python2.6/dist-packages/softwareproperties/ppa.py", line 63, in run
    self.add_ppa_signing_key(self.ppa_path)
  File "/usr/lib/python2.6/dist-packages/softwareproperties/ppa.py", line 92, in add_ppa_signing_key
    print "Error reading %s: %s" % (lp_url, e)
UnicodeDecodeError: 'ascii' codec can't decode byte 0xe3 in position 27: ordinal not in range(128)

ProblemType: Bug
DistroRelease: Ubuntu 10.10
Package: python-software-properties 0.76.7
ProcVersionSignature: Ubuntu 2.6.35-27.48-generic-pae 2.6.35.11
Uname: Linux 2.6.35-27-generic-pae i686
Architecture: i386
Date: Fri Mar 18 11:45:24 2011
EcryptfsInUse: Yes
InstallationMedia: Ubuntu 10.10 "Maverick Meerkat" - Release i386 (20101007)
PackageArchitecture: all
ProcEnviron:
 LANG=ja_JP.utf8
 SHELL=/bin/bash
SourcePackage: software-properties