[Python-checkins] Doc: update PendingDeprecationWarning explanation (GH-12837)

[Miss Islington (bot)]

https://github.com/python/cpython/commit/871ba6c848474959a506e0301628bf826ba11028
commit: 871ba6c848474959a506e0301628bf826ba11028
branch: 3.7
author: Miss Islington (bot) <31488909+miss-islington at users.noreply.github.com>
committer: GitHub <noreply at github.com>
date: 2019-04-15T05:48:31-07:00
summary:

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/filesGH-r273978757
(cherry picked from commit a3283efd30ad52b56d1046138523cbabc6c69daf)

Co-authored-by: Inada Naoki <songofacandy at gmail.com>

files:
M Doc/library/exceptions.rst

diff --git a/Doc/library/exceptions.rst b/Doc/library/exceptions.rst
index 250938003c07..52a505e0a0ff 100644
--- a/Doc/library/exceptions.rst
+++ b/Doc/library/exceptions.rst
@@ -691,16 +691,13 @@ The following exceptions are used as warning categories; see the
 
 .. 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