allow forEach to complete even if it's array grows.

lib/async.js

@@ -82,20 +82,21 @@
             return callback();
         }
         var completed = 0;
-        _forEach(arr, function (x) {
+        for(var i = 0; i < arr.length; ++i){
+            var x= arr[i];
             iterator(x, function (err) {
                 if (err) {
                     callback(err);
                     callback = function () {};
                 }
                 else {
                     completed += 1;
-                    if (completed === arr.length) {
+                    if (completed >= arr.length) {
                         callback(null);
                     }
                 }
             });
-        });
+        }
     };
 
     async.forEachSeries = function (arr, iterator, callback) {

test/test-async.js

@@ -528,6 +528,21 @@ exports['forEach no callback'] = function(test){
     async.forEach([1], forEachNoCallbackIterator.bind(this, test));
 };
 
+exports['forEach with growing array'] = function(test){
+    var arr= [2,3];
+    var iterations = 0;
+    async.forEach(arr, function(x, callback){
+        if (iterations++ == 0) {
+            arr.push(4);
+        }
+        callback();
+    }, function(){
+        test.same(arr, [2,3,4]);
+        test.same(iterations, 3);
+        test.done();
+    })
+};
+
 exports['forEachSeries'] = function(test){
     var args = [];
     async.forEachSeries([1,3,2], forEachIterator.bind(this, args), function(err){