Fix apparent typo in tests (#17247)

Author: jbrockmendel

pandas/tests/indexes/datetimes/test_tools.py

@@ -1112,9 +1112,9 @@ def test_parsers(self):
         result3 = Timestamp('NaT')
         result4 = DatetimeIndex(['NaT'])[0]
         assert result1 is tslib.NaT
-        assert result1 is tslib.NaT
-        assert result1 is tslib.NaT
-        assert result1 is tslib.NaT
+        assert result2 is tslib.NaT
+        assert result3 is tslib.NaT
+        assert result4 is tslib.NaT
 
     def test_parsers_quarter_invalid(self):