Issue #29198: Merge from 3.5

diff --cc Doc/library/typing.rst
index 6c4af4c90cdff7ab9cfa19417ae20708bffe422f,8da71b64a7922f3b6d41dcbe81b2363d207e680d..6c8982ba743526b6c2ba184409e2bda276b7f80c
--- 1/Doc/library/typing.rst
--- 2/Doc/library/typing.rst
+++ b/Doc/library/typing.rst
@@@ -638,14 -625,8 +638,14 @@@ The module defines the following classe
  
  .. class:: AsyncIterator(AsyncIterable[T_co])
  
-   A generic version of :class:`collections.abc.AsyncIterator`.
+    A generic version of :class:`collections.abc.AsyncIterator`.
  
 +.. class:: ContextManager(Generic[T_co])
 +
 +   A generic version of :class:`contextlib.AbstractContextManager`.
 +
 +   .. versionadded:: 3.6
 +
  .. class:: Dict(dict, MutableMapping[KT, VT])
  
     A generic version of :class:`dict`.