Raise KeyError when attempting to slice Layout

holoviews/core/layout.py

@@ -529,6 +529,9 @@ def __getitem__(self, key):
             if key < len(self):
                 return self.data.values()[key]
             raise KeyError("Element out of range.")
+        elif isinstance(key, slice):
+            raise KeyError("A Layout may not be sliced, ensure that you "
+                           "are slicing on a leaf (i.e. not a branch) of the Layout.")
         if len(key) == 2 and not any([isinstance(k, str) for k in key]):
             if key == (slice(None), slice(None)): return self
             row, col = key

tests/testannotations.py

@@ -1,6 +1,6 @@
 import numpy as np
 
-from holoviews import Image, HLine, VLine 
+from holoviews import Image, HLine, VLine, Text, Arrow, Annotation
 from holoviews.element.comparison import ComparisonTestCase
 
 class AnnotationTests(ComparisonTestCase):
@@ -18,3 +18,15 @@ def test_vline_dimension_values(self):
         hline = VLine(0)
         self.assertEqual(hline.range(0), (0, 0))
         self.assertEqual(hline.range(1), (None, None))
+
+    def test_deep_clone_map_select_redim(self):
+        annotations = (Text(0, 0, 'A') + Arrow(0, 0) + HLine(0) + VLine(0))
+        selected = annotations.select(x=(0, 5))
+        redimmed = selected.redim(x='z')
+        relabelled = redimmed.relabel(label='foo', depth=5)
+        mapped = relabelled.map(lambda x: x.clone(group='bar'), Annotation)
+        kwargs = dict(label='foo', group='bar', extents=(0, None, 5, None), kdims=['z', 'y'])
+        self.assertEqual(mapped.Text.I, Text(0, 0, 'A', **kwargs))
+        self.assertEqual(mapped.Arrow.I, Arrow(0, 0, **kwargs))
+        self.assertEqual(mapped.HLine.I, HLine(0, **kwargs))
+        self.assertEqual(mapped.VLine.I, VLine(0, **kwargs))