InstallStepError: Plugin usersetup failed with code 1

Installer crashed with the following exception:

Aug 6 12:35:54 ubuntu plugininstall.py: log-output -t ubiquity umount /target/cdrom
Aug 6 12:35:54 ubuntu finish-install: Disabling CD in sources.list
Aug 6 12:35:54 ubuntu plugininstall.py: Exception during installation:
Aug 6 12:35:54 ubuntu plugininstall.py: Traceback (most recent call last):
Aug 6 12:35:54 ubuntu plugininstall.py: File "/usr/share/ubiquity/plugininstall.py", line 1730, in <module>
Aug 6 12:35:54 ubuntu plugininstall.py: install.run()
Aug 6 12:35:54 ubuntu plugininstall.py: File "/usr/share/ubiquity/plugininstall.py", line 55, in wrapper
Aug 6 12:35:54 ubuntu plugininstall.py: func(self)
Aug 6 12:35:54 ubuntu plugininstall.py: File "/usr/share/ubiquity/plugininstall.py", line 165, in run
Aug 6 12:35:54 ubuntu plugininstall.py: self.configure_plugins()
Aug 6 12:35:54 ubuntu plugininstall.py: File "/usr/share/ubiquity/plugininstall.py", line 538, in configure_plugins
Aug 6 12:35:54 ubuntu plugininstall.py: raise install_misc.InstallStepError("Plugin %s failed with code %s" % (plugin.NAME, ret))
Aug 6 12:35:54 ubuntu plugininstall.py: InstallStepError: Plugin usersetup failed with code 1
Aug 6 12:35:54 ubuntu plugininstall.py:

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: ubiquity 2.10.26
ProcVersionSignature: Ubuntu 3.5.0-23.35~precise1-generic 3.5.7.2
Uname: Linux 3.5.0-23-generic x86_64
NonfreeKernelModules: symap_custom_3.5.0_23_generic_x86_64 symev_custom_3.5.0_23_generic_x86_64
ApportVersion: 2.0.1-0ubuntu17.3
Architecture: amd64
CasperVersion: 1.315.1
Date: Tue Aug 6 08:36:33 2013
InstallCmdLine: file=/cdrom/preseed/ubuntu.seed boot=casper initrd=/casper/initrd.lz quiet splash -- maybe-ubiquity
LiveMediaBuild: Ubuntu 12.04.2 LTS "Precise Pangolin" - Release amd64 (20130213)
MarkForUpload: True
ProcEnviron:
 TERM=unknown
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)