Bugfix: if you define a custom __eq__, you must define a __hash__ too

Also, on Python 3 the stock object.__hash__ raises an error ("unhashable
type"), and we have code that uses Host instances as dict keys.

lib/ansible/inventory/host.py

@@ -41,6 +41,9 @@ class Host:
     def __ne__(self, other):
         return not self.__eq__(other)
 
+    def __hash__(self):
+        return hash(self.name)
+
     def serialize(self):
         groups = []
         for group in self.groups:

test/units/inventory/test_host.py

@@ -33,3 +33,6 @@ class TestHost(unittest.TestCase):
         # __ne__ is a separate method
         self.assertFalse(self.hostA != Host('a'))
 
+    def test_hashability(self):
+        # equality implies the hash values are the same
+        self.assertEqual(hash(self.hostA), hash(Host('a')))