probelm upgrading x-window-system-core

[Adam Mercer <ramercer@gmail.com>]

Hi

I'm tracking side and for the past month or so, aptitude and refused
to upgrade the "x-window-system-core" package saying that it is
broken, at first I thought that this was due to the ongoing change
from xfree86 to xorg.  However sid has been on xorg for a while now
and I am still getting the same error when trying to upgrade the
"x-window-system-core" package

skymoo:/home/ram# aptitude install x-window-system-core
Reading package lists... Done
Building dependency tree... Done
Reading extended state information
Initializing package states... Done
Reading task descriptions... Done
The following packages will be automatically REMOVED:
  libsdl-image1.2-dev libsdl-mixer1.2-dev libsdl-net1.2-dev libsdl1.2-dev
  libsmpeg-dev libvtk4-dev mayavi xlibmesa-glu xlibmesa-glu-dev
The following NEW packages will be installed:
  libglu1-xorg
The following packages will be REMOVED:
  libsdl-image1.2-dev libsdl-mixer1.2-dev libsdl-net1.2-dev libsdl1.2-dev
  libsmpeg-dev libvtk4-dev mayavi xlibmesa-glu xlibmesa-glu-dev
The following packages will be upgraded:
  x-window-system-core
1 packages upgraded, 1 newly installed, 9 to remove and 0 not upgraded.
Need to get 0B/553kB of archives. After unpacking 13.1MB will be freed.
Do you want to continue? [Y/n/?]

why does my system want to remove these packages? Is this a know
problem or am I doing something stupid?

Cheers

Adam