desktop: prevent unintended failures in the livesys initscript

Some of the tweaks we do there may fail if the packages containing
the touched files are not present. Better be careful.

fedora-live-desktop.ks

@@ -27,8 +27,10 @@ cat >> /usr/share/glib-2.0/schemas/org.gnome.desktop.screensaver.gschema.overrid
 lock-enabled=false
 FOE
 
+# make the installer show up
+if [ -f /usr/share/applications/liveinst.desktop ]; then
   # Show harddisk install in shell dash
-sed -i -e 's/NoDisplay=true/NoDisplay=false/' /usr/share/applications/liveinst.desktop
+  sed -i -e 's/NoDisplay=true/NoDisplay=false/' /usr/share/applications/liveinst.desktop ""
   # need to move it to anaconda.desktop to make shell happy
   mv /usr/share/applications/liveinst.desktop /usr/share/applications/anaconda.desktop
 
@@ -36,7 +38,6 @@ cat >> /usr/share/glib-2.0/schemas/org.gnome.shell.gschema.override << FOE
 [org.gnome.shell]
 favorite-apps=['mozilla-firefox.desktop', 'evolution.desktop', 'empathy.desktop', 'rhythmbox.desktop', 'shotwell.desktop', 'openoffice.org-writer.desktop', 'nautilus.desktop', 'anaconda.desktop']
 FOE
-glib-compile-schemas /usr/share/glib-2.0/schemas
 
   # add installer to user menu
   mkdir -p ~liveuser/.local/share/gnome-shell/extensions/Installer@shell-extensions.fedoraproject.org
@@ -59,6 +60,11 @@ function main() {
 }
 FOE
 
+fi
+
+# rebuild schema cache with any overrides we installed
+glib-compile-schemas /usr/share/glib-2.0/schemas
+
 # set up timed auto-login for after 60 seconds
 cat >> /etc/gdm/custom.conf << FOE
 [daemon]
@@ -67,7 +73,9 @@ AutomaticLogin=liveuser
 FOE
 
 # Turn off PackageKit-command-not-found while uninstalled
+if [ -f /etc/PackageKit/CommandNotFound.conf ]; then
   sed -i -e 's/^SoftwareSourceSearch=true/SoftwareSourceSearch=false/' /etc/PackageKit/CommandNotFound.conf
+fi
 
 EOF