Issue #23661: unittest.mock side_effects can now be exceptions again.

This was a regression vs Python 3.4. Patch from Ignacio Rossi
diff --git a/NEWS b/NEWS
index 2aa442a..90fdb0e 100644
--- a/NEWS
+++ b/NEWS
@@ -1,3 +1,6 @@
+- Issue #23661: unittest.mock side_effects can now be exceptions again. This
+  was a regression vs Python 3.4. Patch from Ignacio Rossi
+
 - Issue #23310: Fix MagicMock's initializer to work with __methods__, just
   like configure_mock().  Patch by Kasia Jachim.