Comment 9 for bug 257133

I think I see where you're going.

root@manhack:~# ls -l /usr/lib/libGL.so.1
ls: cannot access /usr/lib/libGL.so.1: No such file or directory

The file that's going to be "overwritten" doesn't even exist, but's its listed as being a part of another package.

root@manhack:~# dpkg -S /usr/lib/libGL.so.1
libgl1-mesa-glx: /usr/lib/libGL.so.1

root@manhack:~# aptitude reinstall libgl1-mesa-glx

root@manhack:~# ls -l /usr/lib/libGL.so.1
ls: cannot access /usr/lib/libGL.so.1: No such file or directory

The dpkg file database doesn't seem to match the actual file system.

I did an 'aptitude remove libgl1-mesa-glx' and aptitude came up with this plan of action:

The following actions will resolve these dependencies:

Remove the following packages:
kubuntu-desktop
libgl1-mesa-dri

Install the following packages:
libgl1-mesa-swx11 [7.2-1ubuntu1 (intrepid)]
libosmesa6 [7.2-1ubuntu1 (intrepid)]

Leave the following dependencies unresolved:
xserver-xorg recommends libgl1-mesa-dri
xserver-xorg-core recommends libgl1-mesa-dri (>= 7.1~rc1)
xserver-xephyr recommends libgl1-mesa-dri (>= 7.1~rc1)

So now I have this:

root@manhack:~# dpkg -S /usr/lib/libGL.so.1
libgl1-mesa-swx11: /usr/lib/libGL.so.1
root@manhack:~# ls -l /usr/lib/libGL.so.1
lrwxrwxrwx 1 root root 19 2008-10-16 14:41 /usr/lib/libGL.so.1 -> libGL.so.1.5.070200

But 'aptitude install nvidia-glx-173' puts me right back to the same spot:

The following NEW packages will be installed:
  dkms{a} fakeroot{a} libgl1-mesa-glx{a} nvidia-173-kernel-source{a} nvidia-glx-173
The following packages will be REMOVED:
  libgl1-mesa-swx11{a}
<snip>
Unpacking nvidia-glx-173 (from .../nvidia-glx-173_173.14.12-1-0ubuntu4_amd64.deb) ...
dpkg: error processing /var/cache/apt/archives/nvidia-glx-173_173.14.12-1-0ubuntu4_amd64.deb (--unpack):
 trying to overwrite `/usr/lib/libGL.so.1', which is also in package libgl1-mesa-glx

root@manhack:~# ls -l /usr/lib/libGL.so.1
ls: cannot access /usr/lib/libGL.so.1: No such file or directory
root@manhack:~# dpkg -S /usr/lib/libGL.so.1
libgl1-mesa-glx: /usr/lib/libGL.so.1

Maybe this makes sense to someone:
root@manhack:~# dpkg-divert --list | grep nvidia
diversion of /usr/lib/libGL.so.1.2 to /usr/lib/nvidia/libGL.so.1.2.xlibmesa by nvidia-glx-173
diversion of /usr/lib/xorg/modules/extensions/libglx.so to /usr/lib/nvidia/libglx.so.xserver-xorg-core by nvidia-glx-173
diversion of /usr/lib32/libGL.so to /usr/lib32/nvidia/libGL.so.xlibmesa by nvidia-glx-173
diversion of /usr/lib32/libGL.so.1 to /usr/lib32/nvidia/libGL.so.1.xlibmesa by nvidia-glx-173
diversion of /usr/lib32/libGL.so.1.2 to /usr/lib32/nvidia/libGL.so.1.2.xlibmesa by nvidia-glx-173
diversion of /usr/lib/xorg/modules/extensions/libGLcore.so to /usr/lib/nvidia/libGLcore.so.xlibmesa by nvidia-glx-173