Bug#274249: kernel-image-2.4.27-powerpc-prep does not install because of an not working .deb package

[Johannes Wischert <johanneswi@gmail.com>]

Package: kernel-image-2.4.27-powerpc-prep
Version: -

During installation of this package i get this error message:

  Internal Error: (=D) is not a directory!

I suppose that is because the variable $image_dir is set to "=D" in
line 35 of  the .deb packages postinst script (the varaiable is
checked validity in line 98 and produces the error message...)
This variable should be set to something usefull like '\boot'