BUG: tiny fix in tests (#39153)

Author: rosagold

pandas/tests/indexing/test_chaining_and_caching.py

@@ -36,7 +36,7 @@ def test_setitem_cache_updating(self):
         # GH 5424
         cont = ["one", "two", "three", "four", "five", "six", "seven"]
 
-        for do_ref in [False, False]:
+        for do_ref in [True, False]:
             df = DataFrame({"a": cont, "b": cont[3:] + cont[:3], "c": np.arange(7)})
 
             # ref the cache