merge 3.5 (#27812)

diff --cc Misc/NEWS
index 01bef3c1a5927e08e497975a970ee5b7c2b54d1e,4b1899938d1f633c53a90b446bb96997bb692161..596f0d048507793c29a9ef1508d33344a9f63a93
--- 1/Misc/NEWS
--- 2/Misc/NEWS
+++ b/Misc/NEWS
@@@ -10,25 -10,9 +10,28 @@@ What's New in Python 3.6.0 beta 
  Core and Builtins
  -----------------
  
 +- Issue #27921: Disallow backslashes in f-strings. This is a temporary
 +  restriction: in beta 2, backslashes will only be disallowed inside
 +  the braces (where the expressions are). This is a breaking change
 +  from the 3.6 alpha releases.
 +  
 +- Issue #27870: A left shift of zero by a large integer no longer attempts
 +  to allocate large amounts of memory.
 +
 +- Issue #25402: In int-to-decimal-string conversion, improve the estimate
 +  of the intermediate memory required, and remove an unnecessarily strict
 +  overflow check. Patch by Serhiy Storchaka.
 +
 +- Issue #27214: In long_invert, be more careful about modifying object
 +  returned by long_add, and remove an unnecessary check for small longs.
 +  Thanks Oren Milman for analysis and patch.
 +
 +- Issue #27506: Support passing the bytes/bytearray.translate() "delete"
 +  argument by keyword.
 +
+ - Issue #27812: Properly clear out a generator's frame's backreference to the
+   generator to prevent crashes in frame.clear().
+ 
  - Issue #27811: Fix a crash when a coroutine that has not been awaited is
    finalized with warnings-as-errors enabled.
  

diff --cc Objects/genobject.c
Simple merge