Cloned input arrays to prevent modification of passed-in values, foun…

…d by @Peter-Donner.  Fixes OverZealous#18

index.js

@@ -34,7 +34,10 @@ function verifyTaskSets(gulp, taskSets, skipArrays) {
 }
 
 function runSequence(gulp) {
-	var taskSets = Array.prototype.slice.call(arguments, 1),
+	// Slice and dice the input to prevent modification of parallel arrays.
+	var taskSets = Array.prototype.slice.call(arguments, 1).map(function(task) {
+			return Array.isArray(task) ? task.slice() : task;
+		}),
 		callBack = typeof taskSets[taskSets.length-1] === 'function' ? taskSets.pop() : false,
 		currentTaskSet,
 

test/main.js

@@ -74,6 +74,14 @@ describe('runSequence', function() {
 		})
 	});
 
+	describe('Input Array Handling', function() {
+		it('should not modify passed-in parallel task arrays', function() {
+			var taskArray = ['task1', 'task2'];
+			runSequence(taskArray);
+			taskArray.should.eql(['task1', 'task2']);
+		});
+	});
+
 	describe('Asynchronous Tasks', function() {
 		it('should run a single task', function() {
 			task1.shouldPause = true;