Switch to using the generic pi gadget repo for classic, use the main branches.

debian/changelog

@@ -1,3 +1,11 @@
+livecd-rootfs (2.651) UNRELEASED; urgency=medium
+
+  * Switch to using the generic pi gadget repo for classic builds. Use the
+    generic branches instead of the 'classic' one as well, as this should now
+    work for both core and classic.
+
+ -- Łukasz 'sil2100' Zemczak <lukasz.zemczak@ubuntu.com>  Fri, 06 Mar 2020 11:52:30 +0100
+
 livecd-rootfs (2.650) focal; urgency=medium
 
   * Support generating a .disk/info file via ubuntu-image from the passed-in

live-build/auto/config

@@ -414,9 +414,15 @@ case $IMAGEFORMAT in
 			# classic images
 
 			# Certain models have different names but are built from the same source gadget tree
+			BRANCH=18
 			case $MODEL in
 				pi-arm64|pi3-arm64)
-					MODEL=pi3 ;;
+					MODEL=pi
+					BRANCH=18-arm64
+					;;
+				pi)
+					BRANCH=18-armhf
+					;;
 			esac
 
 			UBUNTU_IMAGE_ARGS="$UBUNTU_IMAGE_ARGS${PROPOSED:+ --with-proposed}"
@@ -425,7 +431,7 @@ case $IMAGEFORMAT in
 			# We need to look in two places for the gadget tree:
 			# - Launchpad hosted gadgets will be in the snap-gadget repo
 			# - Github hosted gadgets are mirrored into a github-mirror repo
-			git clone git://git.launchpad.net/~canonical-foundations/snap-$MODEL/+git/snap-$MODEL -b classic config/$PREFIX-gadget || git clone git://git.launchpad.net/~canonical-foundations/snap-$MODEL/+git/github-mirror -b classic config/$PREFIX-gadget
+			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
 
 			echo "IMAGEFORMAT=$IMAGEFORMAT" >> config/common
 			echo "SUITE=$SUITE" >> config/common