[dashboard fix]Fix copy_dash unit test (apache#5323)

tests/dashboard_tests.py

@@ -175,7 +175,12 @@ def test_copy_dash(self, username='admin'):
         self.assertEqual(resp['dashboard_title'], 'Copy Of Births')
         self.assertEqual(resp['position_json'], orig_json_data['position_json'])
         self.assertEqual(resp['metadata'], orig_json_data['metadata'])
-        self.assertEqual(resp['slices'], orig_json_data['slices'])
+        # check every attribute in each dashboard's slices list,
+        # exclude modified and changed_on attribute
+        for index, slc in enumerate(orig_json_data['slices']):
+            for key in slc:
+                if key not in ['modified', 'changed_on']:
+                    self.assertEqual(slc[key], resp['slices'][index][key])
 
     def test_add_slices(self, username='admin'):
         self.login(username=username)