Add test for host negation.

tests/test_util.py

@@ -212,3 +212,26 @@ Host *
             raise AssertionError('foo')
         self.assertRaises(AssertionError,
                           lambda: paramiko.util.retry_on_signal(raises_other_exception))
+
+
+    def test_9_host_config_test_negation(self):
+        test_config_file = """
+Host www13.* !*.example.com
+    Port 22
+
+Host *.example.com !www13.*
+    Port 2222
+
+Host www13.*
+    Port 8080
+
+Host *
+    Port 3333
+    """
+        f = cStringIO.StringIO(test_config_file)
+        config = paramiko.util.parse_ssh_config(f)
+        host = 'www13.example.com'
+        self.assertEquals(
+            paramiko.util.lookup_ssh_host_config(host, config),
+            {'hostname': host, 'port': '8080'}
+        )