diff -Nru gdm-3.0.4/debian/changelog gdm-3.0.4/debian/changelog
--- gdm-3.0.4/debian/changelog	2011-12-21 19:44:19.000000000 +0000
+++ gdm-3.0.4/debian/changelog	2012-01-06 12:31:24.000000000 +0000
@@ -1,3 +1,11 @@
+gdm (3.0.4-0ubuntu13) precise; urgency=low
+
+  * debian/gdm.config: Do not show debconf prompt during dist-upgrades.
+    lightdm will be installed and should set itself as default WM.
+    (LP: #911813)
+
+ -- Martin Pitt <martin.pitt@ubuntu.com>  Fri, 06 Jan 2012 13:31:19 +0100
+
 gdm (3.0.4-0ubuntu12) precise; urgency=low
 
   * drop unneeded build-depends on libpolkit-{gtk,gobject}-1-dev
diff -Nru gdm-3.0.4/debian/gdm.config gdm-3.0.4/debian/gdm.config
--- gdm-3.0.4/debian/gdm.config	2011-09-23 21:29:55.000000000 +0000
+++ gdm-3.0.4/debian/gdm.config	2012-01-06 12:31:24.000000000 +0000
@@ -6,6 +6,12 @@
 
 set -e
 
+# do not show question for dist-upgrades to precise, we introduce lightdm there
+# and lightdm sets itself as default
+if [ -n "$RELEASE_UPGRADE_IN_PROGRESS" ]; then
+    exit 0
+fi
+
 # source debconf library
 . /usr/share/debconf/confmodule