Только что взял обновлённые пакеты xorg-7.0.  Кто-нибудь может
объяснить следующее поведение apt:

# apt-get dist-upgrade
Reading Package Lists... Done
Building Dependency Tree... Done
Calculating Upgrade... Done
The following packages will be upgraded
  xorg-x11-extensions-dri
The following packages will be REMOVED:
  glxgears glxinfo libglut libwine libwine-devel wine xorg-x11 xorg-x11-apps
  xorg-x11-drv-ati xorg-x11-drv-i810 xorg-x11-drv-mga xorg-x11-drv-savage
  xorg-x11-drv-sis xorg-x11-drv-tdfx xorg-x11-drv-via xorg-x11-extensions-glx
1 upgraded, 0 newly installed, 18 removed and 0 not upgraded.
Need to get 0B/34.5kB of archives.
After unpacking 52.5MB disk space will be freed.
Do you want to continue? [Y/n] n
Abort.

# apt-get install xorg-x11-extensions-dri
Reading Package Lists... Done
Building Dependency Tree... Done
The following packages will be upgraded
  xorg-x11-extensions-dri
1 upgraded, 0 newly installed, 0 removed and 2 not upgraded.
Need to get 0B/34.5kB of archives.
After unpacking 0B of additional disk space will be used.
Committing changes...
Preparing...                 ########################################### [100%]
1: xorg-x11-extensions-dri   ########################################### [100%]
Done.

# apt-get check
Reading Package Lists... Done
Building Dependency Tree... Done

# apt-get dist-upgrade
Reading Package Lists... Done
Building Dependency Tree... Done
Calculating Upgrade... Done
The following packages will be REMOVED:
  glxgears glxinfo libglut libwine libwine-devel wine xorg-x11 xorg-x11-apps
  xorg-x11-drv-ati xorg-x11-drv-i810 xorg-x11-drv-mga xorg-x11-drv-savage
  xorg-x11-drv-sis xorg-x11-drv-tdfx xorg-x11-drv-via xorg-x11-extensions-glx
0 upgraded, 0 newly installed, 16 removed and 0 not upgraded.
Need to get 0B of archives.
After unpacking 51.6MB disk space will be freed.
Do you want to continue? [Y/n] n
Abort.

При этом для apt доступен репозиторий Сизифа от 2005-12-01 (где лежит
старый xorg) и репозиторий с пакетами xorg-7.0.

Так, закомментировал и Сизиф, оставив только xorg-7.0 - получил:

# apt-get dist-upgrade
Reading Package Lists... Done
Building Dependency Tree... Done
Calculating Upgrade... Done
The following packages will be upgraded
  xorg-x11-apps xorg-x11-extensions-glx
2 upgraded, 0 newly installed, 0 removed and 0 not upgraded.
Need to get 0B/886kB of archives.
After unpacking 0B of additional disk space will be used.
Do you want to continue? [Y/n] 
Committing changes...
Preparing...                 ########################################### [100%]
1: xorg-x11-extensions-glx   ########################################### [ 50%]
Done.

Однако после раскомментирования Сизифа от 2005-12-01 ситуация
повторяется:

# apt-get dist-upgrade
Reading Package Lists... Done
Building Dependency Tree... Done
Calculating Upgrade... Done
The following packages will be REMOVED:
  glxgears glxinfo libglut libwine libwine-devel wine xorg-x11 xorg-x11-apps
  xorg-x11-drv-ati xorg-x11-drv-i810 xorg-x11-drv-mga xorg-x11-drv-savage
  xorg-x11-drv-sis xorg-x11-drv-tdfx xorg-x11-drv-via xorg-x11-extensions-glx
0 upgraded, 0 newly installed, 16 removed and 0 not upgraded.
Need to get 0B of archives.
After unpacking 51.6MB disk space will be freed.
Do you want to continue? [Y/n] n
Abort.