Mythbuntu crashed while installing

[marcatq]

the installation seemed to be going ok and was nearly finished when the screen went blank. I waited for about 15 minutes, then pressed alt+tab. the screen informing me that the installer had crashed came up.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: ubiquity 2.10.29
ProcVersionSignature: Ubuntu 3.8.0-29.42~precise1-generic 3.8.13.5
Uname: Linux 3.8.0-29-generic x86_64
ApportVersion: 2.0.1-0ubuntu17.4
Architecture: amd64
CasperVersion: 1.315.1
Date: Thu Apr 10 18:56:10 2014
InstallCmdLine: file=/cdrom/preseed/mythbuntu.seed boot=casper initrd=/casper/initrd.lz quiet splash -- maybe-ubiquity
LiveMediaBuild: Mythbuntu 12.04.3 "Precise Pangolin" - Release amd64 (20130820)
MarkForUpload: True
ProcEnviron:
 TERM=linux
 PATH=(custom, no user)
 LANG=en_US.UTF-8
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)

[Ubuntu Foundations Team Bug Bot (crichton)]

Exception during installation:
Apr 11 00:41:59 mythbuntu plugininstall.py: Traceback (most recent call last):
Apr 11 00:41:59 mythbuntu plugininstall.py: File "/usr/share/ubiquity/plugininstall.py", line 1730, in <module>
Apr 11 00:41:59 mythbuntu plugininstall.py: install.run()
Apr 11 00:41:59 mythbuntu plugininstall.py: File "/usr/share/ubiquity/plugininstall.py", line 55, in wrapper
Apr 11 00:41:59 mythbuntu plugininstall.py: func(self)
Apr 11 00:41:59 mythbuntu plugininstall.py: File "/usr/share/ubiquity/plugininstall.py", line 200, in run
Apr 11 00:41:59 mythbuntu plugininstall.py: self.install_extras()
Apr 11 00:41:59 mythbuntu plugininstall.py: File "/usr/share/ubiquity/plugininstall.py", line 1257, in install_extras
Apr 11 00:41:59 mythbuntu plugininstall.py: self.do_install(install_misc.query_recorded_installed())
Apr 11 00:41:59 mythbuntu plugininstall.py: File "/usr/lib/ubiquity/ubiquity/install_misc.py", line 856, in do_install
Apr 11 00:41:59 mythbuntu plugininstall.py: with Cache() as cache:
Apr 11 00:41:59 mythbuntu plugininstall.py: AttributeError: __exit__
Apr 11 00:41:59 mythbuntu plugininstall.py: