should add -f option to "rm" in kernel update script

Whenever trying to remove kernels inside the chroot, the postrm script fails:

(LTSP)root@voito:/# aptitude purge linux-image-2.6.22-14-386 linux-ubuntu-modules-2.6.22-14-386
Luetaan pakettiluetteloita... Valmis
Muodostetaan riippuvuussuhteiden puu
Reading state information... Valmis
Reading extended state information
Initializing package states... Valmis
Building tag database... Valmis
The following packages will be REMOVED:
  linux-image-2.6.22-14-386{p}
0 packages upgraded, 0 newly installed, 1 to remove and 0 not upgraded.
Need to get 0B of archives. After unpacking 0B will be used.
Do you want to continue? [Y/n/?] y
Writing extended state information... Valmis
Can not write log, openpty() failed (/dev/pts not mounted?)
(Reading database ... 16999 files and directories currently installed.)
Removing linux-image-2.6.22-14-386 ...
Purging configuration files for linux-image-2.6.22-14-386 ...
Examining /etc/kernel/postrm.d .
run-parts: executing /etc/kernel/postrm.d/ltsp-update-kernels
Cannot open ``/boot/nbi.img-2.6.24-7-386'':File exists
run-parts: /etc/kernel/postrm.d/ltsp-update-kernels exited with return code 1
Failed to process /etc/kernel/postrm.d at /var/lib/dpkg/info/linux-image-2.6.22-14-386.postrm line 320.
dpkg: error processing linux-image-2.6.22-14-386 (--purge):
 subprocess post-removal script returned error exit status 1
Errors were encountered while processing:
 linux-image-2.6.22-14-386
E: Sub-process /usr/bin/dpkg returned an error code (1)
A package failed to install. Trying to recover:
Luetaan pakettiluetteloita... Valmis
Muodostetaan riippuvuussuhteiden puu
Reading state information... Valmis
Reading extended state information
Initializing package states... Valmis
Building tag database... Valmis
(LTSP)root@voito:/#

The solution seems to be to add -f to the "rm" command and to in fact delete the old file _before_ trying to create a new one, rather than after.