Having another process locking the dpkg status database makes jockey crash instead of letting the user know the problem [apport: jockey-backend crashed with SystemError: E:Sub-process /usr/bin/dpkg returned an error code (2)]

[Xavier Bassery]

I have tried to install the driver for a Toshiba printer (Manufacturer-supplied PPD files for Toshiba's Postscript printers) while I had aptitude running in a terminal.
Instead of getting an informative message, jockey-backend crashed.

Steps to reproduce (on a system with hardware managed by jockey):
1. start a package manager with root privilege (aptitude, synaptic)
2. start jockey-gtk
3. try to activate/deactivate any driver listed.
4. crash

ProblemType: Crash
DistroRelease: Ubuntu 11.10
Package: jockey-common 0.9.4-0ubuntu3 [modified: usr/share/pyshared/jockey/detection.py]
ProcVersionSignature: Ubuntu 3.0.0-9.14-generic 3.0.3
Uname: Linux 3.0.0-9-generic i686
NonfreeKernelModules: fglrx
Architecture: i386
Date: Tue Aug 30 17:39:48 2011
ExecutablePath: /usr/share/jockey/jockey-backend
InstallationMedia: Ubuntu 10.04 LTS "Lucid Lynx" - Release i386 (20100429)
InterpreterPath: /usr/bin/python2.7
MachineType: Gigabyte Technology Co., Ltd. P35-DS4
PackageArchitecture: all
ProcCmdline: /usr/bin/python /usr/share/jockey/jockey-backend --debug -l /var/log/jockey.log
ProcEnviron:

ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.0.0-9-generic root=UUID=fb05bdb5-3bf0-4e55-b5f7-4a01917dfc1b ro quiet splash vt.handoff=7
PythonArgs: ['/usr/share/jockey/jockey-backend', '--debug', '-l', '/var/log/jockey.log']
SourcePackage: jockey
Title: jockey-backend crashed with SystemError: E:Sub-process /usr/bin/dpkg returned an error code (2)
Traceback: SystemError: E:Sub-process /usr/bin/dpkg returned an error code (2)
UpgradeStatus: Upgraded to oneiric on 2011-08-27 (2 days ago)
UserGroups:

dmi.bios.date: 05/11/2007
dmi.bios.vendor: Award Software International, Inc.
dmi.bios.version: F4
dmi.board.name: P35-DS4
dmi.board.vendor: Gigabyte Technology Co., Ltd.
dmi.board.version: x.x
dmi.chassis.type: 3
dmi.chassis.vendor: Gigabyte Technology Co., Ltd.
dmi.modalias: dmi:bvnAwardSoftwareInternational,Inc.:bvrF4:bd05/11/2007:svnGigabyteTechnologyCo.,Ltd.:pnP35-DS4:pvr:rvnGigabyteTechnologyCo.,Ltd.:rnP35-DS4:rvrx.x:cvnGigabyteTechnologyCo.,Ltd.:ct3:cvr:
dmi.product.name: P35-DS4
dmi.sys.vendor: Gigabyte Technology Co., Ltd.