Following Dave's changes to the classic pi gadget, switch to using the classic branch for desktop images as well.

live-build/auto/build

@@ -101,7 +101,8 @@ if [ "${IMAGEFORMAT:-}" = "ubuntu-image" ]; then
 		mv output/seed.manifest "$PREFIX".manifest
 	else
 		# First we need to build the gadget tree
-		make -C "config/$PREFIX-gadget" ARCH=$ARCH SERIES=$SUITE
+		make -C "config/$PREFIX-gadget" \
+			ARCH=$ARCH SERIES=$SUITE $GADGET_TARGET
 		ubuntu-image classic $UBUNTU_IMAGE_ARGS \
 			-s $SUITE -p $PROJECT -a $ARCH --subarch $SUBARCH \
 			-O output config/$PREFIX-gadget/install

live-build/auto/config

@@ -507,9 +507,9 @@ case $IMAGEFORMAT in
 					;;
 			esac
 
-			BRANCH="classic"
+			GADGET_TARGET="server"
 			if [ "$SUBPROJECT" = "desktop-preinstalled" ]; then
-				BRANCH="desktop"
+				GADGET_TARGET="desktop"
 			fi
 
 			UBUNTU_IMAGE_ARGS="$UBUNTU_IMAGE_ARGS${SUBPROJECT:+ --subproject \"$SUBPROJECT\"}"
@@ -519,10 +519,12 @@ case $IMAGEFORMAT in
 			# We need to look in two places for the gadget tree:
 			# - Launchpad hosted gadgets will be in the snap-gadget repo
 			# - Github hosted gadgets are mirrored into a github-mirror repo
+			BRANCH="classic"
 			git clone git://git.launchpad.net/~canonical-foundations/snap-$MODEL/+git/snap-$MODEL -b $BRANCH config/$PREFIX-gadget || git clone git://git.launchpad.net/~canonical-foundations/snap-$MODEL/+git/github-mirror -b $BRANCH config/$PREFIX-gadget || git clone git://git.launchpad.net/~canonical-foundations/snap-$MODEL/+git/github-mirror-$ARCH -b $BRANCH config/$PREFIX-gadget
 
 			echo "IMAGEFORMAT=$IMAGEFORMAT" >> config/common
 			echo "SUITE=$SUITE" >> config/common
+			echo "GADGET_TARGET=$GADGET_TARGET" >> config/common
 			echo "UBUNTU_IMAGE_ARGS=\"$UBUNTU_IMAGE_ARGS\"" >> config/common
 
 			echo "Configured ubuntu-image for the following gadget model: $MODEL"