Suppress spurious warning (pandas-dev#49720)

Author: jbrockmendel

pandas/core/frame.py

@@ -8082,7 +8082,9 @@ def update(
  if mask.all():
  continue
 
- self.loc[:, col] = expressions.where(mask, this, that)
+ with warnings.catch_warnings():
+ warnings.filterwarnings("ignore", "In a future version, `df.iloc")
+ self.loc[:, col] = expressions.where(mask, this, that)
 
  # ----------------------------------------------------------------------
  # Data reshaping

pandas/tests/frame/methods/test_update.py

@@ -136,7 +136,8 @@ def test_update_from_non_df(self):
  def test_update_datetime_tz(self):
  # GH 25807
  result = DataFrame([pd.Timestamp("2019", tz="UTC")])
- result.update(result)
+ with tm.assert_produces_warning(None):
+ result.update(result)
  expected = DataFrame([pd.Timestamp("2019", tz="UTC")])
  tm.assert_frame_equal(result, expected)