Bug 544420, backupsnip fails when only adding new directories, r=catlee

git-svn-id: svn://10.0.0.236/trunk@259788 18797224-902f-48f8-a5cc-f745e15eee43

mozilla/tools/release/bin/backupsnip

@@ -54,6 +54,13 @@ for d in $changedDirs; do
     fi
 done
 
+if [ -z "$args" ]; then
+    echo
+    echo 'Nothing to backup. There could be something wrong, or you could'
+    echo 'be creating new directories (eg test snippets for a major update).'
+    exit 0
+fi
+
 pushd $LIVE_SNIPPET_DIR > /dev/null
 echo Running time $TAR cfvz $BACKUP_DIR/$backupDirName.tar.gz $args
 time $TAR cfvz $BACKUP_DIR/$backupDirName.tar.gz $args