Doc: update PendingDeprecationWarning explanation (GH-12837)
Keep the nudge towards DeprecationWarning, but remove the
"Note" markup and generally shorten the description.
Ref: https://github.com/python/cpython/pull/12505/files#r273978757
diff --git a/Doc/library/exceptions.rst b/Doc/library/exceptions.rst
index 2509380..52a505e 100644
--- a/Doc/library/exceptions.rst
+++ b/Doc/library/exceptions.rst
@@ -691,16 +691,13 @@
.. exception:: PendingDeprecationWarning
- Base class for warnings about features which will be deprecated in the
- future.
+ Base class for warnings about features which are obsolete and
+ expected to be deprecated in the future, but are not deprecated
+ at the moment.
- .. note::
- PendingDeprecationWarning was introduced as an "ignored by default"
- version of DeprecationWarning. But :exc:`DeprecationWarning` is also
- ignored by default since Python 2.7 and 3.2.
- There is not much difference between PendingDeprecationWarning and
- DeprecationWarning nowadays. DeprecationWarning is recommended
- in general.
+ This class is rarely used as emitting a warning about a possible
+ upcoming deprecation is unusual, and :exc:`DeprecationWarning`
+ is preferred for already active deprecations.
.. exception:: SyntaxWarning