Allow to provide customized DispVM home directly in the template VM

This significantly speeds up DispVM creation for large customized
homes, since no data has to be copied, and instead CoW is used.

misc/dispvm-prerun.sh

@@ -3,11 +3,13 @@
 apps="/usr/libexec/evinced"
 
 #If user have customized DispVM settings, use its home instead of default dotfiles
+if [ ! -e /home/user/.qubes-dispvm-customized ]; then
 	if [ -e /rw/home/user/.qubes-dispvm-customized ]; then
 		cp -af /rw/home/user /home/
 	else
 		cat /etc/dispvm-dotfiles.tbz | tar -xjf- --overwrite -C /home/user --owner user 2>&1 >/tmp/dispvm-dotfiles-errors.log
 	fi
+fi
 
 for app in $apps ; do
     echo "Launching: $app..."

vm-systemd/mount-dirs.sh

@@ -79,11 +79,13 @@ if [ -e /var/run/qubes-service/qubes-dvm ]; then
     touch /etc/this-is-dvm
 
     #If user have customized DispVM settings, use its home instead of default dotfiles
+    if [ ! -e /home/user/.qubes-dispvm-customized ]; then
         if [ -e /rw/home/user/.qubes-dispvm-customized ]; then
             cp -af /rw/home/user /home/
         else
             cat /etc/dispvm-dotfiles.tbz | tar -xjf- --overwrite -C /home/user --owner user 2>&1 >/tmp/dispvm-dotfiles-errors.log
         fi
+    fi
 else
     mount /home
 fi