linux-base 2.6.32-11~bpo50+1 fails to install

[Richard Kettlewell <rjk@greenend.org.uk>]

rjk@rackheath:~$ dpkg --audit
The following packages have been unpacked but not yet configured.
They must be configured using dpkg --configure or the configure
menu option in dselect for them to work:
 linux-image-2.6.32-bpo.4-amd64 Linux 2.6.32 for 64-bit PCs

The following packages are only half configured, probably due to problems
configuring them the first time.  The configuration should be retried using
dpkg --configure <package> or the configure menu option in dselect:
 linux-base           Linux image base package

rjk@rackheath:~$ really dpkg --configure linux-base
Setting up linux-base (2.6.32-11~bpo50+1) ...
Invalid output format udev. Choose from value,
        device, list, or full
Invalid output format udev. Choose from value,
        device, list, or full
Invalid output format udev. Choose from value,
        device, list, or full
Invalid output format udev. Choose from value,
        device, list, or full
Undefined subroutine &DebianKernel::DiskId::_system called at 
/var/lib/dpkg/info/linux-base.postinst line 1004, <STDIN> line 10.
dpkg: error processing linux-base (--configure):
 subprocess post-installation script returned error exit status 9
Errors were encountered while processing:
 linux-base

ttfn/rjk