Fix a bug in the clone method of the layouts (#1349)

* Fix clone method of layout

* Add tests to clone method of layour

panel/layout/base.py

@@ -247,7 +247,7 @@ def clone(self, *objects, **params):
                              % type(self).__name__)
         p = dict(self.param.get_param_values(), **params)
         del p['objects']
-        return type(self)(*objects, **params)
+        return type(self)(*objects, **p)
 
     def append(self, obj):
         """

panel/tests/layout/test_base.py

@@ -402,6 +402,46 @@ def test_layout_clone_kwargs(panel):
     assert clone.sizing_mode == 'stretch_height'
 
 
+@pytest.mark.parametrize('panel', [Column, Row])
+def test_layout_clone_no_args_no_kwargs(panel):
+    div1 = Div()
+    div2 = Div()
+    layout = panel(div1, div2, width=400, sizing_mode='stretch_height')
+    clone = layout.clone()
+
+    assert layout.objects[0].object is clone.objects[0].object
+    assert layout.objects[1].object is clone.objects[1].object
+
+    assert clone.width == 400
+    assert clone.sizing_mode == 'stretch_height'
+
+
+@pytest.mark.parametrize('panel', [Column, Row])
+def test_layout_clone_objects_in_kwargs(panel):
+    div1 = Div()
+    div2 = Div()
+    layout = panel(div1, div2)
+    clone = layout.clone(
+        objects=(div2, div1), 
+        width=400, sizing_mode='stretch_height'
+    )
+
+    assert layout.objects[0].object is clone.objects[1].object
+    assert layout.objects[1].object is clone.objects[0].object
+
+    assert clone.width == 400
+    assert clone.sizing_mode == 'stretch_height'
+
+
+@pytest.mark.parametrize('panel', [Column, Row])
+def test_layout_clone_objects_in_args_and_kwargs(panel):
+    div1 = Div()
+    div2 = Div()
+    layout = panel(div1, div2)
+    with pytest.raises(ValueError):
+        layout.clone(div1, objects=div1)
+
+
 def test_widgetbox(document, comm):
     widget_box = WidgetBox("WidgetBox")