ignore successive metadata errors with the same message

lib/metadata.js

@@ -198,6 +198,7 @@ Meta.commands = Object.keys(commands);
 Meta.createLineHandler = function (ref, errorHandler) {
     ref.meta = {};
     ref.index = 0;
+    ref.logged = {};
 
     return function (err, line) {
         if (err) {
@@ -216,10 +217,15 @@ Meta.createLineHandler = function (ref, errorHandler) {
         var index = ref.index++;
         if (typeof(line) === 'undefined') { return; }
 
+
         if (Array.isArray(line)) {
             try {
                 handleCommand(ref.meta, line);
             } catch (err2) {
+                var code = err2.message;
+                if (ref.logged[code]) { return; }
+
+                ref.logged[code] = true;
                 errorHandler("METADATA_COMMAND_ERR", {
                     error: err2.stack,
                     line: line,