kill the snappy os build if the initramfs-tools-ubuntu-core package is not found

debian/changelog

@@ -1,3 +1,11 @@
+livecd-rootfs (2.399) UNRELEASED; urgency=medium
+
+  * live-build/ubuntu-core/hooks/25-create-generic-initrd.chroot:
+    kill the snappy os build if the initramfs-tools-ubuntu-core package
+    is not found
+
+ -- Oliver Grawert <ogra@ubuntu.com>  Sun, 10 Apr 2016 17:23:05 +0200
+
 livecd-rootfs (2.398) xenial; urgency=medium
 
   * switch snappy package builds from "snappy build" to "snapcraft snap"

live-build/ubuntu-core/hooks/25-create-generic-initrd.chroot

@@ -5,6 +5,9 @@ set -ex
 IVER="$(dpkg -s initramfs-tools-ubuntu-core | \
 			sed -n '/^Version:/{s/^[^: ]*: \([^: ]*\).*/\1/;p;}')"
 
+# fail the build if we did not find the snappy initrd package
+[ -n "$IVER" ] || exit 1
+
 # force lzma
 mkdir -p /etc/initramfs-tools/conf.d
 echo "COMPRESS=lzma" >/etc/initramfs-tools/conf.d/snappy-generic-initrd.conf