Fix issue with scene component when using YAML aliases.

YAML aliases/anchors can make repetitive configuration sections easier
to deal with.  However when dealing with dictionaries, care needs to be
taken to not modify the original anchor since PyYAML utilizes a
reference when encountering an alias instead of a copy of the
dictionary.

homeassistant/components/scene.py

@@ -73,8 +73,9 @@ def _process_config(scene_config):
 
     for entity_id in c_entities:
         if isinstance(c_entities[entity_id], dict):
-            state = c_entities[entity_id].pop('state', None)
+            entity_attrs = c_entities[entity_id].copy()
-            attributes = c_entities[entity_id]
+            state = entity_attrs.pop('state', None)
+            attributes = entity_attrs
         else:
             state = c_entities[entity_id]
             attributes = {}

tests/components/test_scene.py

@@ -32,6 +32,60 @@ class TestScene(unittest.TestCase):
             'scene': [[]]
         }))
 
+    def test_config_yaml_alias_anchor(self):
+        """
+        Tests the usage of YAML aliases and anchors.  The following test scene
+        configuration is equivalent to:
+
+        scene:
+          - name: test
+            entities:
+              light_1: &light_1_state
+                state: 'on'
+                brightness: 100
+              light_2: *light_1_state
+
+        When encountering a YAML alias/anchor, the PyYAML parser will use a
+        reference to the original dictionary, instead of creating a copy, so
+        care needs to be taken to not modify the original.
+        """
+        test_light = loader.get_component('light.test')
+        test_light.init()
+
+        self.assertTrue(light.setup(self.hass, {
+            light.DOMAIN: {'platform': 'test'}
+        }))
+
+        light_1, light_2 = test_light.DEVICES[0:2]
+
+        light.turn_off(self.hass, [light_1.entity_id, light_2.entity_id])
+
+        self.hass.pool.block_till_done()
+
+        entity_state = {
+            'state': 'on',
+            'brightness': 100,
+        }
+        self.assertTrue(scene.setup(self.hass, {
+            'scene': [{
+                'name': 'test',
+                'entities': {
+                    light_1.entity_id: entity_state,
+                    light_2.entity_id: entity_state,
+                }
+            }]
+        }))
+
+        scene.activate(self.hass, 'scene.test')
+        self.hass.pool.block_till_done()
+
+        self.assertTrue(light_1.is_on)
+        self.assertTrue(light_2.is_on)
+        self.assertEqual(100,
+                         light_1.last_call('turn_on')[1].get('brightness'))
+        self.assertEqual(100,
+                         light_2.last_call('turn_on')[1].get('brightness'))
+
     def test_activate_scene(self):
         test_light = loader.get_component('light.test')
         test_light.init()