ubiquity crashed with ImportError in /usr/lib/ubiquity/ubiquity/misc.py: No module named six

[Fabio Marconi]

dup of bug 1023527 with dbgsym added

ProblemType: Crash
DistroRelease: Ubuntu 12.10
Package: ubiquity 2.11.11
ProcVersionSignature: Ubuntu 3.5.0-4.4-generic 3.5.0-rc6
Uname: Linux 3.5.0-4-generic x86_64
ApportVersion: 2.3-0ubuntu4
Architecture: amd64
CasperVersion: 1.319
Date: Wed Jul 11 18:34:13 2012
ExecutablePath: /usr/lib/ubiquity/bin/ubiquity
InstallCmdLine: noprompt cdrom-detect/try-usb=true persistent file=/cdrom/preseed/ubuntu.seed boot=casper initrd=/casper/initrd.lz quiet splash -- maybe-ubiquity
InterpreterPath: /usr/bin/python2.7
LiveMediaBuild: Ubuntu 12.10 "Quantal Quetzal" - Alpha amd64 (20120711.2)
ProcCmdline: /usr/bin/python /usr/lib/ubiquity/bin/ubiquity gtk_ui
ProcEnviron:
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
 TERM=unknown
PythonArgs: ['/usr/lib/ubiquity/bin/ubiquity', 'gtk_ui']
SourcePackage: ubiquity
Title: ubiquity crashed with ImportError in /usr/lib/ubiquity/ubiquity/misc.py: No module named six
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: