slightly adjust the version handling for the core snap, drop suffix from kernel snap version string

debian/changelog

@@ -1,4 +1,4 @@
-livecd-rootfs (2.420ubuntu1) UNRELEASED; urgency=medium
+livecd-rootfs (2.420) UNRELEASED; urgency=medium
 
   [ Łukasz 'sil2100' Zemczak ]
   * Remove the ubuntu-pd project from the scripts
@@ -7,6 +7,7 @@ livecd-rootfs (2.420ubuntu1) UNRELEASED; urgency=medium
 
   [ Oliver Grawert ]
   * sanitize the version number of the ubuntu-core snap
+  * sanitize the version number of the kernel snap
 
  -- Oliver Grawert <ogra@ubuntu.com>  Tue, 19 Jul 2016 13:59:16 +0200
 

live-build/auto/build

@@ -257,7 +257,9 @@ if [ "$PROJECT:$SUBPROJECT" = "ubuntu-core:system-image" ]; then
             mkdir -p $rootfs/$dir
         done
 
-        VERSION="$(lsb_release -r -s)"
+        # get a proper version from the chroot
+        . $rootfs/etc/os-release
+        VERSION="$(echo $PRETTY_NAME | sed 's/[^0-9.]*//g')"
 
         CORENAME="ubuntu-core"
         cat > $rootfs/meta/snap.yaml <<EOF
@@ -508,7 +510,7 @@ EOF
         ln -s $kernel kernel.img
         kvers="$(ls vmlinuz-*|sed 's/^.*vmlinuz-//;s/-[a-z.]*$//')"
 
-        VERSION=$kvers+$(date +20%y%m%d.%H-%M)
+        VERSION=$kvers
 
         cat > meta/kernel.yaml <<EOF
 version: $kvers