Don't outright remove fstab for ubuntu-server:live, that breaks grub-legacy-ec2.

live-build/auto/config

@@ -713,15 +713,14 @@ EOF
 		;;
 esac
 
-case $PROJECT in
-	ubuntu-server)
+if [ $PROJECT = ubuntu-server ] && [ $SUBPROJECT != live ]; then
 	cat > config/hooks/100-remove-fstab.chroot <<EOF
 #! /bin/sh
 rm -f /etc/fstab
 EOF
-		;;
+fi
 
-	ubuntukylin)
+if [ $PROJECT = ubuntukylin ]; then
 	cat > config/hooks/100-ubuntukylin.chroot <<EOF
 #! /bin/sh
 set -e
@@ -731,8 +730,7 @@ if [ -x \$HOOK ]; then
 fi
 exit 0
 EOF
-		;;
-esac
+fi
 
 if $BINARY_REMOVE_LINUX; then
 	cat > config/binary_rootfs/excludes << EOF