Fix unpacking of negative timestamps from msgpack

- Update the work of PR influxdata#734 to correctly interpret negative timestamps
- Update unit test for pre-unix epoch date with negative timestamp

influxdb/client.py

@@ -1243,7 +1243,7 @@ def _parse_netloc(netloc):
 
 def _msgpack_parse_hook(code, data):
     if code == 5:
-        (epoch_s, epoch_ns) = struct.unpack(">QI", data)
+        (epoch_s, epoch_ns) = struct.unpack(">qI", data)
         timestamp = datetime.datetime.utcfromtimestamp(epoch_s)
         timestamp += datetime.timedelta(microseconds=(epoch_ns / 1000))
         return timestamp.isoformat() + 'Z'

influxdb/tests/client_test.py

@@ -575,7 +575,8 @@ def test_query_msgpack(self):
         example_response = bytes(bytearray.fromhex(
             "81a7726573756c74739182ac73746174656d656e745f696400a673657269"
             "65739183a46e616d65a161a7636f6c756d6e7392a474696d65a176a67661"
-            "6c7565739192c70c05000000005d26178a019096c8cb3ff0000000000000"
+            "6c7565739292c70c05000000005d26178a019096c8cb3ff0000000000000"
+            "92c70c05ffffffffffff7360075bcd15cb4000000000000000"
         ))
 
         with requests_mock.Mocker() as m:
@@ -590,7 +591,7 @@ def test_query_msgpack(self):
 
             self.assertListEqual(
                 list(rs.get_points()),
-                [{'v': 1.0, 'time': '2019-07-10T16:51:22.026253Z'}]
+                [{'v': 1.0, 'time': '2019-07-10T16:51:22.026253Z'}, {'v': 2.0, 'time': '1969-12-31T14:00:00.123457Z'}]
             )
 
     def test_select_into_post(self):