Fix AttributeError in exception handler

The exception handler of save_state() caused an AttributeError
because it tried to get the output attribute of the Exception,
which does not exist in general. Added a test to cover this
scenario.

Change-Id: I36acdee1f8782b17c234f6b250facc5c8d0aaf87

octavia/amphorae/backends/utils/haproxy_query.py

@@ -165,6 +165,5 @@ class HAProxyQuery(object):
         except Exception as e:
             # Catch any exception - may be socket issue, or write permission
             # issue as well.
-            LOG.warning("Unable to save state: %(err)s %(output)s",
+            LOG.warning("Unable to save state: %r", e)
-                        {'err': e, 'output': e.output})
             return False

octavia/tests/unit/amphorae/backends/utils/test_haproxy_query.py

@@ -159,3 +159,15 @@ class QueryTestCase(base.TestCase):
             self.q.save_state(filename)
 
             mock_fh.write.assert_called_once_with('DATA')
+
+    def test_save_state_error(self):
+        """save_state() should swallow exceptions"""
+        filename = 'state_file'
+
+        query_mock = mock.Mock(side_effect=OSError())
+        self.q._query = query_mock
+
+        try:
+            self.q.save_state(filename)
+        except Exception as ex:
+            self.fail("save_state() raised %r unexpectedly!" % ex)