Fix task filter issue

tests/units/TaskFilterTest.php

@@ -0,0 +1,19 @@
+<?php
+
+require_once __DIR__.'/Base.php';
+
+use Model\TaskFilter;
+
+class TaskFilterTest extends Base
+{
+    public function testCopy()
+    {
+        $tf = new TaskFilter($this->container);
+        $filter1 = $tf->create();
+        $filter2 = $tf->copy();
+
+        $this->assertTrue($filter1 !== $filter2);
+        $this->assertTrue($filter1->query !== $filter2->query);
+        $this->assertTrue($filter1->query->condition !== $filter2->query->condition);
+    }
+}