Revert "Remove redundant condition"

This reverts commit ae2376a.

Author: mroeschke

pandas/tests/series/indexing/test_setitem.py

@@ -1025,7 +1025,7 @@ class TestSetitemNAPeriodDtype(SetitemCastingEquivalents):
     def expected(self, key):
         exp = Series(period_range("2000-01-01", periods=10, freq="D"))
         exp._values.view("i8")[key] = NaT._value
-        assert exp[key] is NaT
+        assert exp[key] is NaT or any(x is NaT for x in exp)
         return exp
 
     @pytest.fixture